Not really sure what you're saying to be honest. Christianity makes sense to many people who it didn't previously make sense to. It has to, or it would never have gained traction in the first place.
Compare the number of people who have converted to Christianity due to evidence, logic, and rational arguments, versus the number of people who have been converted to Christianity through their emotions and subjective experiences, and what I'm saying should become much clearer.
Honestly, magicmiles, and this isn't intended as a slight, Christianity doesn't strike me as being particularly sensible to begin with. It's a system designed to make people feel special - that there's a Heavenly Father out there making sure that everything is under control, so even if bad things happen, they're ultimately for a good reason. So Christianity makes people feel that they don't have to try to make sense of things - they have God on their side.
So those friends of yours, I don't think they really understand Christianity any better now than they did before, they just feel better now. Christianity isn't about understanding things at all. It's about feeling good about things. Indeed, I think it is for that reason that many of the atheists here stopped being Christians - because they stopped feeling good about things, and when they prayed to the god they worshiped then, there was no answer. As a result, they had to try to make sense of things, instead of just being able to feel good about them.