Christianity is a religion of suffering. How can that be a crutch? As a Christian you have to give up many things to be a fully committed believer. For example, 2 Timothy 2:3 (NRSV) states, "Share in suffering like a good soldier of Christ Jesus." We're in a fight (hence the soldier reference) and like an Army unit, we all share in the tough times, but also the good times. John 16:33 (NRSV) states, "I have said this to you, so that in me you may have peace. In the world you face persecution. But take courage; I have conquered the world!" Yes we will be persecuted as Christians. However -- as that passage adds at the end -- we take comfort that even though the world persecutes us, Christ conquered the world.
For examples of that suffering, think of how Christians, according to Romans 13:13 (NRSV), "let us live honorably as in the day, not in reveling and drunkenness, not in debauchery and licentiousness, not in quarreling and jealousy." Ok, so as a Christian we are to not get drunk first of all. Alcohol can be a crutch. Then, licentiousness is, according to dictionary.com, to be "sexually unrestrained." It says we are NOT to be unrestrained so, in other words, Christians are to abstain from premarital sex. A clearer passage on that is Hebrews 13:4 (NRSV), "Let marriage be held in honor by all, and let the marriage bed be kept undefiled; for God will judge fornicators and adulterers." (Fornication is having consensual sex outside of marriage.) We are also commanded not to quarrel, not be jealous...wow, that's a lot.
I'm not going to pretend that all Christians keep these perfectly, all are sinful. However as a Christian we are to strive for this and pray for strength from God. Also worth a quick note, we avoid these things out of love for God, it's not to save us -- that's through grace by faith.
Now, let's see...atheists can have sex as often as they want (it's their choice), they can get drunk whenever they want (again, their choice)...you can fight, you can be jealous. Atheism is a very FREE form of thought. And Christianity is a crutch? Sure sounds like the opposite is true -- I need to have sex, I need a lot of alcohol, shut up you're wrong, I really wish I had that new car...
I could use many passages in the Bible that refer to abstaining from sex, avoiding getting drunk and many other things Christians are to give up to and follow what Jesus said in Luke 9:23 (NRSV), "Then he said to them all, “If any want to become my followers, let them deny themselves and take up their cross daily and follow me." Christians are even to deny themselves, not rely on themselves but on God because we are sinful.
I think my point has been made that Christianity isn't a crutch, it's a hard lifestyle -- but it's the most rewarding life as it is living for God rather than yourself. So while it is suffering, we as Christians also have joy because of Christ's saving work on the cross: "My brothers and sisters, whenever you face trials of any kind, consider it nothing but joy," James 1:2 (NRSV).