The English word "religion" is translated into Arabic by Deen. Nonetheless, the Arabic language is rich, so this word has many meanings.
It means compulsion, and Dayyaan means the Most Irresistible.
It may also mean reward and reckoning, and means the Day of Recompense. It also has other meaning such as: Obedience, custom, matter, law and politics. Dayyaan also means the governor, the ruler the one who legislates. 
There are other meanings of the word deen as well, such as: “a particular law”, “a statute” “an ordinance”, “recompense”, “judgement”, “reckoning”, etc. but when the preposition “la” OR “laam” لis used with deen دين, it particularly means, “obedience”. See the following ayath:
…lahu ad-deen… لَهُ الدِّينَ
Qur’an98:5] which means: “Ad-Deen [i.e. obedience] is only to Him [i.e. Allah]”
The ayath 42:13 indicates IQAAMAT-e-DEEN, i.e. the setting up or establishment of Ad-deen.
أَقِيمُوا الدِّينَ “…aqeemoo alddeena…” [42:13] which means: “…Establish Ad-Deen…”
As Ad-deen is of Allah [10:22, 16:52, 29:65, 31:32, 39:2, 39:11, 40:14, 40:65, 98:5], so “…Establish Ad-Deen…” is actually “…Establish Allah’s Deen”, which means “…establish a way of life in which obedience is only of Allah…”
Now let us see ayath 3:19, which says, إِنَّ الدِّينَ عِنْدَ اللَّهِ الإسْلامُ
The primary meanings of Al-ISLAM are:
- Submission and obedience to Allah
1. The Creed (shahadah),
2. Daily Prayers (salah),
3. Almsgiving (zakath),
4. Fasting during Ramadan (sawm) and
5. The Pilgrimage to Makkah (hajj) at least once in a lifetime, if you have means.
To belief in
It is to worship Allah سبحانه و تعالىas that if you are seeing Him, for though you don't see Him, He,verily, sees you…..
Prophet Muhammad(S) remarked: He was Gabriel (the angel). He came to you in order to instruct you in matters of Deen (religion). SAHIH MUSLIM hadith no.8, 10 
The basic Qur'anic term, namely, deen, had different connotations among the Arabs, and their use of it and its various derivatives revolved round one or other of the following four basic concepts or relationships, etc., namely:
The word had not, however, attained the status of a formal term as such before the revelation of the Qur'an. The Arabs were not very clear in their minds as to the concepts involved nor were their ideas lofty in this context and that is the reason why the word had not found its way into the terminology of any systematic and recognized school of thought. It was in the Qur'an in which, obviously because the word was particularly suited to its purpose, that it was given very clear-cut and definite connotations, and it was this aspect which made the word one of the most important in the Qur'anic terminology. In that terminology, it stands for the entire way of life, of which the composite factors are:
And, as in other cases, the Qur'an employs the term, on different occasions, in one or more of the above four senses, but where the intention is to imply the whole way of life, it uses the definite article 'al' before the word, to make it read 'al-Deen' Examples of such different uses are as follows:
It is Allah (Glory be to Him) Who has made the earth as a resting place for you, and the sky a canopy, and has given you shape-and what a piece of work it is!-and has provided for your sustenance things pure and wholesome; such is Allah (Glory be to Him), your Lord. So Glory be to Allah (Glory be to Him), the Lord of the Worlds. He is the Living (One); there is no god but He; so address your prayers to Him, making your deen exclusive for Him. Praise be to Allah (Glory be to Him), the Lord of the Worlds. (Qur'an. Surah Baqrah2:21,22)
Say (O Muhammad): "I have been forbidden to give my 'ibadah to Allah (Glory be to Him), making my deen exclusive to Him, and bidden to be the first of His obedient-servants."… Say (O' Mohammed): "It is Allah (Glory be to Him) to Whom I give my 'ibadah, making my deen exclusive for Him; (and as for you,) give yours to whoever or whatsoever you may wish to give it to (if you will not listen to me but wish to continue in your wrong ways)"... And as for those who are careful and wise enough not to give their 'ibadah to taghoot, and who turn to Allah (Glory be to Him) alone, there (surely) are glad tidings for them. (Qur'an. Surah 39:11,14,17)
Indeed, We have sent down to you the Book, [O Muhammad], in truth. So worship Allah , [being] sincere to Him in religion.Unquestionably, for Allah is the pure religion. And those who take protectors besides Him [say], "We only worship them that they may bring us nearer to Allah in position." Indeed, Allah will judge between them concerning that over which they differ. Indeed, Allah does not guide he who is a liar and [confirmed] disbeliever.(Qur'an. Surah 39:2-3)
And to Him belongs all, there is in the heavens and the earth, and Deen is (rightly) His alone. Why is it, then, that you fear others the way yon should fear Him (alone)? (Qur'an. Surah 16:52)
Do (the non-believers) want some deen other than Allah’s (Glory be to Him), and this despite the fact that to Him are subservient, willingly or unwillingly, all the creatures and thing, that constitute the universe and to Him it is that they shall (all) return'? (Qur'an. Surah 3:83)
And they were not bidden except that they give their 'ibadah to Allah (Glory be to Him), making their deen exclusive for Him (and Him alone). (Qur'an. Surah Al-Bayyinah98:5)
In all the above examples the word has been employed to signify the vesting of the Supreme authority in Allah (Glory be to Him) alone, tacit acknowledgement of that fact, and complete unquestioning obedience and submission to that authority. The making of one's deen exclusive for Allah (Glory be to Him) means that one should not treat anyone other than Allah (Glory be to Him) as having the ultimate authority, domain, and rulership over the uniayath and should so make one's obedience and submission exclusive for Him that there is no association of anyone else with Him in this respect. What is required is that there should not be even the slightest element of association and treatment of anyone else as having sovereignty or authority and being entitled to obedience and submission as of independent right.
Say (O' Muhammad): "If you suffer from any doubts as to the details, or validity or rationality of my deen, then let it be known to you that I do not give me ‘ibadah to anyone other than Allah (Glory be to Him) He Who (having alone the power in this regard) causes you to die, and I have been bidden to be of the believers (in Him), and to set my conduct and coarse wholly and solely according to the Deen and not to become one of those who associate others with Allah (Glory be to Him). (Qur'an. Surah Yunus10:104-105)
Authority vests in Allah (Glory be to Him) alone. (And) He has Commanded that we do not give our 'ibadah to any accept Him; this is the Deen, right and proper. (Qur'an. Surah Yousuf 12:40)
And to Him belong all who are in the heavens and the earth. All are subservient to Him, ... He has propounded to you a similitude from your own (experience). Is any of your slaves a partner with you in the bounty We have conferred upon you? Do you make them equal partners in your ownership of your possessions? ... The truth is that these misguided people follow their own wrong and baseless notions, ideas and desires without proper knowledge... So you (O' Muhammad) set your face straight upon the Deen, and follow the natural course meant by Allah (Glory be to Him) for men It is not right that Allah’s (Glory be to Him) Design be interfered with. This is the right and proper Deen and yet many a people know this not. (Qur'an. Surah Ar-Rum 30: 26,28-30).
The adulterer, and the adulteress, let them both be given a hundred stripes each, and let not pity overcome you in a matter of Allah’s (Glory be to Him) Deen [ Adultery, in Islam, is the commission of the sexual act between a male end a female not married to each other. The fact that it has been committed through mutual consent is no mitigation of the offence.] (Qur'an. Surah Nur 24:2)
In Allah’s (Glory be to Him) Writ, the number of months has always been twelve to a year, from the day He erected the heavens and the earth; of which (twelve) four are sacred; this is the true and straight deen (usage). (Qur'an. Surah Taubah 9:36)
And thus did those whom they associated with Allah (Glory be to Him) make it appear a commendable act in the eyes of the mushrikeen [That is, the people guilty of shirk, the association of others with God.] to slay their children in order to lead them to their own destruction, and cause confusion in their deen. (Qur'an. Surah Anam 6:138)
Have they taken some people to be partners (with Allah (Glory be to Him)) who prescribe ways for them in the nature of deen, for which they have had no permission from Allah (Glory be to Him). (Qur'an. Surah ash-Shura42:21)
For you, your deen, and for me mine own. (Qur'an.Surah Kafirun109:6)
In all these ayaath, the word deen has been used to mean the law, rules or regulations, shari'ah, or code of conduct, or that system of thought and action which a person subscribes to and lives by. If the ultimate authority for the law or code, etc., which is followed, is Allah (Glory be to Him) Himself, then the person concerned in observing Allah’s (Glory be to Him) deen; if it owes us itself to the commandments of a monarch, then he is in the monarch's Deen; if it is prescribed by some priests or pundits or other religious leaders then he is observing their deen; and if it has been laid down by the family, the clan or the tribe, or the national body-politic, then he is following their deen. In other words, the basic, critical factor as to the deen a person follows is the ultimate authority responsible for it.
Verily, that which you are promised (that is, life after death) is true, and deep (the reckoning and the judgement and retribution) must indeed come to pass. (Qur'an. Surah Adh- dhariyat 51:5-6)
Have you noticed the person who denies Deen (the life after death)? He is one who spurns the orphan, and does not urge people to feed the needy and the indigent. (Qur'an. Surah Maun 107:1-3)
And what do you know of the Day of Deen? Yea, what (little) do you know of the Day of deen. That is the Day when no human being shall be able to be of any service to another, the Day on which all authority and dispensation will tangibly be in the hands of Allah (Glory be to Him). (Qur'an. Surah Infitar 82:17-19)
Obviously, in these ayaath, the word has been used to imply both the final reckoning when men shall have been raised from the dead as well as the reward or punishment which will follow.
In the examples given above, the word has been used more or less in the four different senses in which the Arabs employed it before the advent of Islam. It remains to give a few examples of its use to mean a whole way of life in which a person gives his submission and obedience to someone whom he regards as having the ultimate authority, shapes his conduct according to the bounds and laws and rules prescribed by that being, looks to him for recognition honour, and reward for loyal service, and fears the disgrace or punishment that could follow any lack on his part. There is perhaps no word in the terminology of any country or people-other than Muslims-which would comprehensively embrace all these factors. The word `state' as employed in our own day does, to some extent, approximate to the sense, but even this word lacks the far wider connotation which would bring it on a par with the word Deen. Examples of the Qur'anic use of deen in this comprehensive sense are as follows:
Here, the word deen obviously embraces belief in Allah (Glory be to Him), as the Supreme Authority, and submission and obedience to Him as a logical requirement following on from such recognition, the raising after death and calling to account, pronouncing judgement, and pronouncing and implementing reward or punishment, as also the code which prescribes what is permitted and what is forbidden. It is after having detailed these four factors that the Qur'an accuses the people involved of not making the true deen their deen too.
And, said the Pharaoh: Leave me to slay Musa(Peace be upon Him), and then let him call upon his Rabb (to save him). (I must slay him for) I am very much afraid that he might change your deen or disturb the peace of land. (Qur'an. Surah Ghafir 40:26)
In the light of all the details contained in the Qur'an of what transpired between the Pharaoh and Musa (on whom be peace), it is clear that the word deen as used here does not stand only for `religion' but covers also the whole politico-social and cultural set-up. The Pharaoh's contention was that if Musa (on whom be peace) succeeded in his mission, there would come about a revolutionary change in which the prevailing way of life with the Pharaoh as the ultimate authority, together with all the laws, rules, and customs etc., would be uprooted, and either a whole new way of life would take its place on completely new foundations, or no new way of life would establish itself at all and the land would fall a prey to anarchy.
Indeed, the religion in the sight of Allah is Islam.(Qur'an. Surah Ale-Imran 3:19)
And whosoever seeks any deen other than `Islam', it shall never receive acceptance. (Qur'an. Surah Ale-Imran 3:85)
It is He-Allah (Glory be to Him)-Who sent his Messenger with true Guidance, and with the True Deen to make it triumph over other deens, caring naught what annoyance this may cause to those who associate others with Him. (Qur'an. Surah Taubah 9:33)
And continue the fight against them until all mischief is effectively destroyed and the only deen holding away is Allah’s (Glory be to Him) deen and none other. (Qur'an. Surah Anfal 8:39)
When Allah’s (Glory be to Him) help arrives, and victory results, and you see people joining in Allah’s (Glory be to Him) deen in crowd, then Glorify your Rabb, and beg forgiveness of Him, for He is the Oft-Forgiving? and that you seek forgiveness of Him (for any failing you may have unwittingly committed); Verily He is the Oft-Forgiving.] (Qur'an. Surah Nasr110:1-3)
In all these ayaath, THE WORD DEEN STANDS FOR THE COMPLETE WAY OF LIFE, INCLUDING MAN'S BELIEFS, HIS MORAL PRINCIPLES, AND HIS BEHAVIOUR IN ALL WALKS OF LIFE.
In the first two ayaath it is said that the right and proper way of life intended by God for man is that founded on obedience to Him and conformity to His Laws. Any other way of life, based on someone else's supposed right to ultimate authority and submission to it, has not the slightest place in Allah’s (Glory be to Him) scheme for man and is hence as wholly unacceptable to Him. And this is but natural. Man is God's creature and lives in His Domain and God is his Master and Sustainer. How then, can God be expected to consent that man may spend his life in obedience to someone else similarly His creature and dependant, and look to that someone for guidance?
The third ayath proclaims that Allah (Glory be to Him) sent His Messenger (may peace be upon him) with the true Deen, the way of life meant by Him for man, which is known as Islam, and it was the primary purpose of the Prophet's mission that he should make this Deen prevail in their stead and triumph over all other ways of life.
In the fourth, the believers have been ordered to fight all non-believers until mischief-that is, every system of thought, belief, and action which is not based on recognition of Allah (Glory be to Him) as the Supreme Authority, and which therefore will perpetually remain the source of all strife and unrest-has been wiped out, and entire humanity adopts the approved way of life, Allah’s (Glory be to Him) Deen.
The fifth ayath was revealed when, after 23 years of prolonged struggle the Islamic Revolution had overcome all resistance in Arabia, when Islam had established itself and been universally accepted as a system of belief, thought, morality, culture, etc., in all its details and in all walks of life, and delegation after delegation from all parts of the country was arriving to pledge allegiance to it, and the Holy Prophet (on whom be peace) was thus witnessing the fulfillment of his mission. After referring to this, the ayath goes on to tell the Prophet (on whom be peace) not to let any sentiments of vanity or pride arise in his mind and make him feel that he owed the success to himself. Allah (Glory be to Him), the Rabb of all, and of the Prophet too (peace be upon him), is alone free of all shortcomings and failings and complete and perfect in every respect. Therefore, any credit for the success which crowned the Prophet's efforts, was due rightfully to Him alone, and the Prophet should Glorify Him, and utter His praises, and beg forgiveness for any possible shortcomings that might have occurred during his 23 years long term of service to his Lord. [ May Allah’s (Glory be to Him) choicest peace and blessings be upon this most pious and perfect of human beings, our intercessor with Allah (Glory be to Him), on the Day of Judgement!