There are a lot of issues with the common Christian concept of an immortal soul that goes to heaven or hell. If you're of a certain mindset, it's easy to render the whole structure ridiculous if you just ask enough questions. Questions like:

-How much of a person's personality is tied to their "soul"? Does one retain memories of one's life? Does one still experience emotions and sensations that are, in life, tied to hormones and nerve impulses?
-If a person has a brain injury and it changes their personality, and they then convert or unconvert, does it count? When they die, does the personality of their soul still reflect who they are now, or does it revert to their pre-injury personality?
-If a soul is generated when sperm cell meets egg cell, at what point in their union is the soul created? If a soul appears with the first cell, then that cell splits into what will become two identical twins, which one gets the first soul, and which one gets the second?

That's by no means a comprehensive list. Of course, the fact that one can nitpick a narrative (any narrative) into pedantic silliness in no way renders that narrative untrue or unimportant. There are, however, two traps that this road leads to that must be avoided.

The first is to declare that the lack of comprehensive answers means that the narrative is untrue and unimportant. The second is to seize on some arbitrary answer and declare it definitive truth. It's hard to say which pitfall is worse, but the second is certainly more dangerous.