Question:
Answer:
Our salvation is worked out over the course of a lifetime and not instantly upon creation because we are embodied persons and not angels. Angels, being pure spirit, made their decision for or against God at the moment of their creation. If they chose against God, they fell forever with no chance of repentance. That is because pure spiritual beings are not subject to change over time. Humans, being embodied persons, are subject to change over time, and therefore can continue to repent until death.
Catholics sometimes wonder if it is unfair to the angels not to have a chance to repent; you’re wondering if it is unfair to humans to have to go through life. The answer in both cases is that angels and humans were created differently, and our respective judgments correspond to the gifts and the limitations we each experience according to our nature. For more information, I recommend reading Theology for Beginners by Frank Sheed.