I'm pretending to be a christian for the better part of five years now
Okay, but why do you need to pretend you're a Christian?
I don't know, It all happened in the past. I needed something to be proud of
It is good to want to make up for the past, but it is not good to pretend to be something that you are not. People will feel betrayed when they find out.
There is nothing wrong with me lying about something that happened to me in the past.
Even if it has happened in the past and if no one was really harmed by your actions, you know for your own good that you have lied and that alone makes it something that is morally wrong. I do suggest you don't pretend who you are and make sure that you are honest with all of your dealings in the future.