Halal is an Arabic word meaning allowed, lawful or permitted. The halal is that in which there is no sin in doing it, but if a person intends to enhance his obedience to Allah by doing it, and then he will be rewarded for this intention. The opposite of halal is haram, which means unlawful or prohibited, this term restrict only for food but it carries varies range of areas such as Finance, Market, Dressing, etc. Most diets and foods are considered to be Halal unless Islamic Law specifically prohibits them.
The principle of natural permissibility is not only limited to things and objects but also includes all human actions and behavior not related to acts of worship, which may be termed living habits or day-to-day affairs. Here again, the principle is that these are allowed without restriction, with the exception of a small number of things which are definitely prohibited by the Law-Giver, Allah, Who says: ...He (Allah) has explained to you what He has made haram for you.... (Qur’an 6:119) including both objects and actions.
The case is different, however, in relation to acts of worship. These are purely religious acts which can be taken only from what Allah Himself reveals. Concerning this we have a sound hadith, Prophet Muhammad (S):“Whoever innovates anything in this matter of ours (i.e., Islam), that is not part of it will have it rejected.” (al-Bukhaari, no. 2697; Muslim, no. 1718)
In Islam, Halal is term which is taken in a broader sense, it covers not only food and drink, but all the matters of daily life. It is a term selecting any object or an action which is permitted to use or involve in. Therefore Halal and Haram is decided only through Qur’an and Sunnah.
The Asl al-deen or basic principle of religion Islam is that the halaal is that which Allah سبحانه و تعالى and His Messenger have permitted, and the haraam is that which Allah and His Messenger have forbidden. The religion is that which Allah and His Messenger have prescribed. No one has the right to go beyond the limits of the Straight Path with which Allah sent His Messenger. Allah says (interpretation of the meaning): “And verily, this is My straight path, so follow it, and follow not (other) paths, for they will separate you away from His path. This He has ordained for you that you may become Al-Muttaqoon (the pious)” [al-An’aam 6:153]
The Messenger of Allah (peace be upon him) brought complete Deen to us. He (peace be upon him), by the command of Allah, has described to us Halaal and Haraam, in the light of which we can know the permissibility or the prohibition of anything.
Allah said that, “The Prophet commands them what is just and prohibits what is evil”.
“So take what the Messenger assigns to you and deny yourselves that
So the Almighty has said: "O (you) Messengers! Eat of the tayyibat [all kinds of halal (legal) foods], and perform righteous deeds." [23:51] and the Almighty has said: "O you who believe! Eat of the lawful things that We have provided you." [2:172]"
Haafiz Ibn Katheer (rahimahullah) said:
“This includes everyone who comes up with an innovation (Bid`ah) for which he has no evidence from the Sharee’ah, or whoever declares something lawful that Allah has forbidden, or whoever declares something unlawful that Allah has permitted, only because it suits his opinions or whim to do so.” (Tafseer Ibn Katheer: 4/75)
The Basic principle or Asl Refers to the Permissibility of Things. The first principle is that all that Allah سبحانه و تعالى has created and the benefits derived from them are for humanity’s use are permissible. The first asl (Asl, plural usool, denotes origin, source, foundation, basis, fundamental or principle), or principle, established by Islam is that the things which Allah has created and the benefits derived from them are essentially for man's use, and hence are permissible. Nothing is haram except what is prohibited by a sound and explicit Nas (Nas denotes either a ayath of the Qur'an or a clear, authentic, and explicit sunnah (practice or saying) of Prophet Muhammad. These are the two main sources of Islamic law, i.e., its Shari'ah. (Trans.)) from the Law-Giver, Allah Subhanahu wa Ta'ala. If the Nas is not sound, as for example in the case of a weak hadith, or if it is not explicit in stating the prohibition, the original principle of permissibility applies.
The scholars of Islam have derived this principle of the natural usability and permissibility of things from the clear verses of the Qur'an. For example, Allah says: It is He who created all that is in the earth for you.... (2:29) He has subjected to you, from Himself, all that is in the heavens and all that is on the earth.... (45:13) Do you not see that Allah has subjected to you whatever is in the heavens and what is on earth, and has showered upon you His favors, both apparent and unseen? (31:20)
It cannot be that Allah, may He be glorified, would create all these things, give man control over them, count them as His favors upon him, and subsequently inform him that their use is prohibited; how could this be when He created all this for man's use and benefit? Indeed, He has prohibited only a few things for specific reasons, the wisdom of which will be discussed later.
In Islam the sphere of prohibited things is very small, while that of permissible things is extremely vast. There is only a small number of sound and explicit texts concerning prohibitions, while whatever is not mentioned in a nas as being lawful or prohibited falls under the general principle of the permissibility of things and within the domain of Allah's favor. In this regard the Prophet (peace be on him) said: What Allah has made lawful in His Book is halal and what He has forbidden is haram, and that concerning which He is silent is allowed as His favor. So accept from Allah His favor, for Allah is not forgetful of anything. He then recited, "And thy Lord is not forgetful." (19:64) (This hadith was reported by al-Hakim, classified as sahih (sound), and quoted by al-Bazzar.)
Salman al-Farsi reported that when the Messenger of Allah (peace be on him) was asked about animal fat, cheese, and fur, he replied, "The halal is that which Allah has made lawful in His Book and the haram is that which He has forbidden, and that concerning which He is silent He has permitted as a favor to you." Sunan Ibn Majah 3367
Thus, rather than giving specific answers to what the questioner had asked, the Prophet (peace be on him) referred to the general criterion for determining the halal and the haram. Accordingly, it is sufficifor us to know what Allah has made haram, since what is not includedin it is pure and permissible. The Prophet (peace be on him) also said: Allah has prescribed certain obligations for you, so do not neglect them; He has defined certain limits, so do not transgress them; He has prohibited certain things, so do not do them; and He has kept silent concerning other things out of mercy for you and not because of forgetfulness, so do not ask questions concerning them. (Reported by aI-Darqutni and classified as hasan (good) by al-Nawawi.)
In Islam, the sphere of forbidden things is very small, while that of permissible things is vast. In relation to acts of worship, the principle is limitation: Nothing can be legislated in this regard except what God Himself has legislated. But as far as living habits are concerned, the principle is freedom, because nothing can be restricted in this regard except what God Himself and the Messenger, as based upon His Revelation, have forbidden. No rabbi, priest, king, or sultan has the right to forbid something permanently to God’s servants. 
1. Your Supplication (Dua’) may not be answered
2. You will incur the wrath of Allah سبحانه و تعالى if you slaughter in the name of others
3. If you agree with the Mushrik (idolaters) that dead meat is halal, it will render you a Mushrik