Does ones immortal soul begin at our mortal birth or does it exist an eternity before our mortal birth?
Not sure don't remember.
You don’t remember your immortal souls before your birth, but neither do you remember your immortal soul after your death. Because of this, the same argument for your belief in having an immortal soul applies for it potentially existing before your birth.
Since an immortal soul exists for all of eternity, it would seem logical that the immortal soul would begin along with the rest of existence. We have been able to determine that the known Universe dates back at least 10 billion years.
This mean that it is likely you immortal soul has experienced 10 billion years or more of existence before your birth.
After our mortal death, what does the immortal soul do for all the rest of eternity? Anything you want if you make it that far.
If we have an immortal soul, then, by definition, it will exist through all eternity. So there would be no question of making it, because by having an immortal soul you are guaranteed to make it.
Now, you might propose that immortal souls go different places after death, but that is irrelevant to making it that far.
After you die it is very reasonable to estimate the known universe will continue at least another 10 billion years. Either way you look at it, your single mortal life will consist of an extremely small portion of the time your immortal soul exists.
Therefore, the vast majority of the time your immortal soul will be experiencing something other than your current mortal life.
To say that during this time your immortal soul can do anything you want does not make sense, unless when you are not bound to you current mortal life you are the supreme absolute god of the existence your immortal soul resides in. Is that what you are saying?
Otherwise, you immortal soul must interact in some social structure with other immortal souls. This means social rules ad laws.
If you do you'll also know what not to do. By knowing what not to do you'll see.
How will you know what not to do? If you can do anything you want, there is nothing that comes under “what not to do” because you can do anything you want.
But then, you are also implying that by the time you die you will know some vital knowledge. Do you think everyone learns what they must by the time they die? If they don’t, do they ever get a chance to continue learning?
Speaking of learning, since the vast majority of time an immortal soul exists is spent somewhere other that your current mortal life, does your immortal soul ever learn and develop during that other time?
In other words, your immortal soul learns and develops during your mortal life which is probably going to be less than 100 years in length. During the other 20,000,000,000+ years your immortal soul is doing stuff, is it learning and developing?