I would say their past would be a reason why I WOULD go out with them. It means they have come a long way, and can be much stronger, have their priorities straight, and are more mature. The only thing I would be concerned about is they may possibly be too serious and focused on their spirituality to be able to chill out and have fun anymore, which I have seen happen to a lot of people in that type of situation. But not to everyone.
And Sam is absolutely correct.