When you were a child did you ever pretend to be someone you were not? A cowboy? A princess? Did you dress up and take on the role of that character? You felt like that character for a little while as you played the game. But when you took the costume off, who did you become once again? You became yourself once again.
Just like when we put a costume on, it doesn't change our identity. We are who we are. Either we are dead in our trespasses and sins. Or we are alive in Christ. Our identity is sealed by God. It can't be changed. When we are in Christ we are new and holy beings.
Does this make sense? It's faith. According to your faith. Believing that what God said He would do He actually did the moment we surrendered to Christ by faith. It's His work. And it's done. Finished. Complete. So we rest in His completed work. Fully enjoying the God who set us free. Our hearts overflowing with thanksgiving, for God did for us what we could never have done.