If you encounter the disbelievers in a battle, strike-off their heads. Take them as captives when they are defeated. Then you may set them free as a favor to them, with or without a ransom, when the battle is over. This is the Law. Had God wanted, He could have granted them (unbelievers) victory, but He wants to test you through each other. The deeds of those who are killed for the cause of God will never be without virtuous results.