This whole topic is called by Aristotle "metaphysics" because it is beyond physics.
Theology is a part of metaphysics.
Aristotle mostly speculates logically about "The Prime Mover", which is a corollary to San Tomas Aquinas' "First Cause".
Aristotle noticed that planets, the Sun, the Moon, comets, and asteroids all move through the heavens, therefore he surmised that Someone must have put these all into motion, Someone greater than them all.
San Tomas Aquinas noticed that all living things on this Earth die eventually, therefore he speculated logically that all things were created by Someone that cannot die.
The Two are Both related. They are essentially the same phenomenon.
In modern times you can believe in The Big Bang if you want, but you must also then ask philosophically, who caused it? That which caused it is the First Cause and Prime Mover -- a God.
Jewish, Christian, and Muslim (in that order) theology each tell us there are daemons which are diabolical (these are Greek words from The New Testament) and which were cast down to the Earth from God's Heaven where they originally were created with all the other angels and The Seven Archangels, Seraphim, and Cherubim of God.
The daemons are immortal, same as our own souls, same as the angels and the Seven Archangels, Seraphim, and Cherubim of God, and God himself.
The daemons try us to see if we will act diabolical just like them, or if we will act instead like the other angels of God.
The reward for us is then based on our works. Not on our faith alone. Faith without works is dead. See Matthew Chapter 25 starting at verse 31:
"When the Son Of Man (Jesus) shall come in his glory, and all the holy angels with him, then shall He sit upon the thrown of his glory. And before Him shall be gathered all nations. And He shall separate them one from another, as a shepherd divideth his sheep from the goats ... ."