The antichrist doctrine of the immortal soul is one of the earliest major lies introduced into Christianity. This lie has massive implications. This deception came from Gnosticism and found its way into the early second century church by those influenced by Gnosticism and eventually became an accepted doctrine. About 180 A.D., Irenaeus explains how this lie came from the Gnostics and crept into the Christian church:

"Some who are reckoned among the orthodox go beyond the prearranged plan for the exaltation of the just, and are ignorant of the methods by which they are disciplined beforehand for incorruption. They thus entertain HERETICAL opinions. For the heretics, not admitting the salvation of their flesh, affirm that immediately upon their death THEY SHALL PASS ABOVE THE HEAVENS... to that Father whom they have feigned.... For they do not choose to understand, that if these things are as they say, the Lord Himself, in whom they profess to believe, did not rise again upon the third day; but immediately upon His expiring on the cross, undoubtedly DEPARTED ON HIGH, LEAVING HIS BODY to the earth....
Against Heresies, Book V, 21

Gnosticism is where Trinity world got its notions of an immortal soul and what happens when you die. They in fact do believe they will pass above the heavens when they die and they do believe that God the Son upon dying was not dead but alive and well leaving his body behind on the cross. Irenaeus contrasts this lie with the truth which is that our hope is the resurrection of the body when Jesus comes in glory.