So, what I'm saying is: I think that the suit is Prophet. If you were to wear that suit, then you'd be Prophet. You'd no longer be you. You'd be gone. You would probably cease to exist as you. It would just be your physical body in there, being operated by the suit known as Prophet. There was indeed a man named Lawrence Barnes, but he unwittingly sacrificed himself to become the suit, and the suit became him - his call sign, known as Prophet. So now, it doesn't matter who wears that suit: it's always Prophet.
I don't know if I'm explaining it accurately, but basically: just put Crysis 2 and 3 together. Also, think back to how different Prophet was in Crysis 1 once he was exposed to the aliens.
Edit: X is the default for Weapon Customization. Don't think of it as just the default for switching ammo. ;) Anyway, I've changed almost all of the controls to suit me. So, I forgot what the defaults are.