Had to take a moment to compose a logical thread.
If our souls were not in existence prior to conception, then does it not follow that our souls are a chemically creation? A creation of the joining of an ovum and a sperm? Thus, if our souls were created at the moment of conception, how can we make a claim that our souls are eternal? Further, how can we make the claim that our soul is created by God?
We are taught that our bodies are merely vessels that house our souls for our time during our mortal period. Our mortal bodies are temporary, our souls are eternal. That like Christ, we would know pain, sickness, torment, hunger, weakness and temptation - something that a soul (without a body) would not be able to conceive of. We are told that after we die, and are resurrected we will no longer know illness, pain, hunger or the torments of corruption.
During the Battle of Heaven, Lucifer took 1/3 of the Heavenly Host with him, and they were cast out. Among the 2/3rd who remained were a mixture of the faithful souls, but there were also very likely a goodly number of “fence-sitters” who simply lacked the courage to throw-in with either side.
My faith teaches that 2 plans were offered up to God. Lucifer offered up a plan that souls would live their life on earth and all would be compelled to do good, and by not being given a choice, all would return to God in Heaven, and the Glory of this would go to Lucifer.
Christ offered a plan that the souls would come to earth, and would have free will to do as they would. Some would seek to do evil and would cause great harm to others; while others would strive to do good. Some souls would return to God in Heaven, but many would be lost. Only the truly deserving souls would return - for their true nature would be given reign during their mortal lifespan. Knowing that sin was inevitable, Jesus offered his life as a sacrifice for the forgiveness of all those who would ask forgiveness in his name.
Earth is merely a filter, the stage on which we determine our ultimate reward or our ultimate punishment. Some of us will be rewarded for the choices we made, others will be punished - but we will all be dealt with fairly.
Take a battery, some insultated wire, and a nail and assemble a simple electromagnet. None of the parts were posessed of magnetism until all the parts came together, and a chemical reaction happend. Is that magnetism a chemical creation?
Lots of things we differ on here.
Our souls are not chemical. A soul is no form of mass-energy or space-time. That would be Manichean.
Also, that does not mean they are eternal. Catholics differentiate between eternal and forever. Nothing is co-eternal with God. Souls are not eternal; but they are immortal and forever. Eternal means a no-space, no-time condition because no change is possible, and God does not change since any change would be away from perfection. Since God created space and time as well as all the matter in it, only He is eternal, and everything else is forever. Forever is an infinite space, infinite time condition, which applies to us.
Humans are not just souls, but body and soul. The Resurrection will be resurrection of a body also, a perfect spiritual body that does not experience the ills that affect our bodies now because of sin. Sin brought death into the world. Once of the consequences of this doctrine is that Mary, who was conceived without sin, never experienced sickness, and she was assumed into Heaven rather than died. This was what was supposed to happen to Adam and Eve if they never bit the apple. Bodies are not just vessels or suits we walk around with for a time, but will be reconstituted at the Resurrection.
Note that when Jesus said we would “Be like the angels” he was speaking in the context of marriage. There is no need for immortals to conceive children. It did not necessarily mean we would be disembodied souls.
The idea that we would exist as only souls after death without bodies is a little Manichean, and very Gnostic. Catholics reject that.
I have heard something about this story about two plans, but not much because we do not consider it canonical. At the very least we do not hold Satan on the same level as Jesus. Satan is a creature, and Creation was by the Father, through the Son, and with the Holy Spirit. Jesus, as being One with the Father, is eternal and not a creature. He was begotten of the Father from eternity, not created. He came from eternity for a time and returned to eternity without changing. This is part of the mystery that humans cannot wrap their minds around.
The filter idea is a useful metaphor. After death, there is no salvation from Hell once entered. The parable of the sheep and the goats tell us that. I doubt there are many Christians sects that do not believe that.