You

 If I have to love someone, let it be you.

 If I have to hate someone, let it be you.

 If I have to trust someone, let it be you.

 If I have to judge someone, let it be you.

You be the one I believe, 

You are the one I doubt,

You be the reason for my gain,

You be the reason of my pain,

You are the reason for my theism,

You are the reason for my atheism,

You become my faith,

You become my unfaith

You be my loyalty,

You be my treachery,

 Whatever be it, wherever be it,

 Let it be you, Only you.