In my opinion, the player is both the angel and Angelica (since they're said to be a merged consciousness in the same body) depending on your ending Forcas either sees that Angelica's consciousness is stronger, or the angel's is.
What interested me is how no matter which ending you get, Forcas is on your side. In the "silent salvation" ( where you prove Angelica is conscious) he's openly against the angel possessing Angelica and promises to help her regain control of her mind.
While in the other ending, when you don't act like the pastor's wife would, the people of the church turn against you. But Forcas is saddened by your fate, saying he wanted you to act as the wife to buy you (the angel) time and help you survive in the human world.
I hope my rant made sense, what I mean in the end is that what Forcas tells you to do is always the good thing for you, no matter if you end up the Angel or Angelica. He's always changing his reason for making you act like the wife, so it looks like he wants to help.