Whether he's religious or not, or decides to pray or not - is separate to how good a pilot he is. (And honestly, sometimes these things are outside of his hands).
There are plenty of religious people who are good pilots.
There are plenty of non-religious people who are good pilots.
Unless you have some meaningful data, you can't really make a conclusion either way.
In terms of asking somebody to pray - I've never been particularly offended by that, no matter what the faith of the person. (I have my own faith). Unless of course they were asking me to pray for something that in itself is offensive - such as say, death to all Jews or something.
If they're asking me to pray for say, the safe return of their husband, or that their puppy dog might recover - I'd feel like a real jerk if I just said no, instead of just going, um sure? If they want me to pray with them in their language, sure.