It is evil to justify killing (unborn babies) by the happy outcome of eternity for the one killed. This same justification could be used to justify killing one-year olds, or any heaven-bound believer for that matter. The Bible asks the question: "Shall we sin that grace may abound?" (Romans 6:1) And: "Shall we do evil that good may come?" (Romans 3:8). In both cases the answer is a resounding NO. It is presumption to step into God's place and try to make the assignments to heaven or to hell. Our duty is to obey God, not to play God.
John PiperWhat defines us as Christians is not most profoundly that we have come to know him but that he took note of us and made us his own.
John PiperA Christian is not a person who believes in his head the teachings of the Bible. Satan believes in his head the teachings of the Bible! A Christian is a person who has died with Christ, whose stiff neck has been broken, whose brazen forehead has been shattered, whose stony heart has been crushed, whose pride has been slain, and whose life is now mastered by Jesus Christ.
John Piper