As for the prohibition of food I quote below one relevant Qur'anic verse: "Forbidden to you (for food) are: dead meat, blood, the flesh of swine, and that on which hath been invoked the name of other than Allah; that which hath been killed by strangling, or by a violent blow, or by a headlong fall, or by being gored to death; that which hath been (partly) eaten by a wild animal; unless ye are able to slaughter it (in due form); that which is sacrificed on stone (altars); (forbidden) also is the division (of meat) by raffling with arrows: that is impiety..."(5:3) Your doubt is why God should prohibit any kind of food, while God is the One who has created everything. Well, everything has a purpose in Gods scheme. If God tells His obedient servants (that is to say, those humans whom are willing to follow His laws) that they are prohibited from eating a particular kind of food, then the duty of His servants is just to follow that command. That is a test from God, which those who love God follow literally. It is not a question of certain things having been created by someone other than God. God is the Creator of everything; God is in command of everything; God is the Lawmaker and the Lawgiver; He has the Dominion and the Power of command. This is the Islamic view of the universe and our duty is to understand His commands and obey. It is a matter of submitting to his Will, not a matter of who created what is prohibited and who didnt. I hope this brief answer gives you an idea about the wisdom of yielding to the only One Who is worth surrendering to in complete submission.