Every facet of personal identity we associate with the soul, the human brain has a physical analog for. Therefore, the human brain is most likely the soul or the device used to connect us to our souls.
The human brain is a biological machine. A machine never does anything at random. If the outputs of two brains which received the exact same input are different, then the designs of the individual brains must be different. If the outputs of two brains that function the same way are the same, they must have received different inputs.
Every decision you make is inevitable. Free will is controlled by the function of your brain and information or experience received from the outside. If you decide to change yourself, you were "destined" to, because the function of your brain, coupled with input information, made you make that decision.
God's will shall be served no matter what because he is omnipotent, therefore it is not up to you to decide if you go to heaven or hell. Your decisions are influenced by your environment, and even the brain that makes these decisions can be called part of the "environment," since free will is just a mechanical function subject to the same rules of logic as the environment.
No matter what you do, God will have his way.
Therefore, if God wants you, you can do nothing.
You can live your life the same way you did before. The only differences in how you live will be those that God makes, those you cannot change.
God does not want us to think we know better than him.
Therefore, we should only do action in God's name if he expressly demands it, not if we independently decide to do it.
Ergo, the best follower of God does nothing differently than he did before, so you can't distinguish believers and non-believers.
All's I'm trying to do is play Devil's Advocate tho. I'm not taking either stance on this, I'm just trying to reason thru this. You, on the other hand, will not entertain any new idea you don't like or can't understand. Not telling you to believe any differently, just don't discredit ideas you can't digest ISFJ.