Lyric discussion by drummerboypbc 

Cover art for Wrong Body lyrics by As Cities Burn

I think this song may be referring to the fact that the desires of the flesh often make us look back in regret. The will of the soul is not to sin, but the will of the body sins easily. Therefore being in the "wrong body", would essentially be saying that the desires of his heart and flesh don't match. With this, the song is also, as previously said, about the amazing grace of God.