Hardest thing with this lyric is what to call it. "Yesterday" is out of the question, as is "yesterday once more." Both are already taken. I'm totally open to suggestions about the title and the lyrics.
As you know, titles can be used over and over on any number of different songs, but I do understand why you wouldn't want to use "Yesterday"--that one's too iconic. "Yesterday Once More" is less so, but I agree it would be nice to come up with something more original. I actually like the one you have: "Yesterday When You Still Loved Me". Incidentally, you missed another good one that's already been used: "The Way We Were".
And another idea might be "The Way We Were Before".
On to the lyric itself.
I’ll hide inside a holy church to wash away my sin.
Maybe God can find a way to feel alright again.
As written, that second line actually means maybe God can find a way for
himself to feel all right again. I know no one will misunderstand the meaning, but I believe it's always better if it can be written so it really says exactly what it means. I think it makes it stronger.
Maybe something like "Where God can find a way to make me feel all right again" ?? Or "So God can find a way..." And depending on how your melody works, you might even be able to alter it to say, "Maybe God can find a way to make me feel all right again."
Yesterday when you still loved me, not long ago before.
Looking for my will to live since you walked out that door.
Why can’t we go back and be the way we were before?
Why? Well, actually the protagonist knows why they can't go back to be the way they were before. S/he screwed up, that's why. So, in my opinion, s/he isn't going to be asking that question, as it's all too painfully and already obvious. I suggest considering something more like, "If only we could go back to be the way we were before!" The rhythm isn't quite right, though. How about, "I wish that we could go back to the way we were before" or "If only we could go back to the way we were before" ??
Those are the issues that I noticed. If anything is helpful, great! If not, no worries.
I think this is an original and creative approach to a common theme. Nice work!
Vicki