The best reason to not be a Christian is that you can live exactly the kind of life you wish without any moral restraints.The Bible describes this type of lifestyle which is becoming increasingly popular,especially in the homosexual community:
2 Peter 2:12-14
12 But these people speak against things they do not understand. They are like animals that act without thinking, animals born to be caught and killed. And, like animals, these false teachers will be destroyed. 13 They have caused many people to suffer, so they themselves will suffer. That is their pay for what they have done. They take pleasure in openly doing evil, so they are like dirty spots and stains among you. They delight in deceiving you while eating meals with you. 14 Every time they look at a woman they want her, and their desire for sin is never satisfied. They lead weak people into the trap of sin, and they have taught their hearts to be greedy. God will punish them!