It's a great question, TJ73. Although I am not a theist, I hope you don't mind if I contribute the following for your consideration, from the Qur'an:
[47.34] Surely those who disbelieve and turn away from Allah's way, then they die while they are unbelievers, Allah will by no means forgive them.
[3.91] Surely, those who disbelieve and die while they are unbelievers, the earth full of gold shall not be accepted from one of them, though he should offer to ransom himself with it, these it is who shall have a painful chastisement, and they shall have no helpers.
[2.161] Surely those who disbelieve and die while they are disbelievers, these it is on whom is the curse of Allah and the angels and men all;
[ 18.102] ... Surely We have prepared hell for the entertainment of the unbelievers.
[ 76.4] Surely We have prepared for the unbelievers chains and shackles and a burning fire.
[ 35.34] And (as for) those who disbelieve, for them is the fire of hell; it shall not be finished with them entirely so that they should die, nor shall the chastisement thereof be lightened to them: even thus do We retribute every ungrateful one.
[ 46.34] And on the day when those who disbelieve shall be brought before the fire: Is it not true? They shall say: Aye! by our Lord! He will say: Then taste the punishment, because you disbelieved.
[ 74.31] And We have not made the wardens of the fire others than angels, and We have not made their number but as a trial for those whodisbelieve, that those who have been given the book may be certain and those who believe may increase in faith, and those who have been given the book and the believers may not doubt, and that those in whose hearts is a disease and the unbelievers may say: What does Allah mean by this parable? Thus does Allah make err whom He pleases, and He guides whom He pleases, and none knows the hosts of your Lord but He Himself; and this is naught but a reminder to the mortals.
Although most sane, compassionate human beings (like yourself) would forgive investigation and doubt as part of being human, and part of thinking and part of living an enlightened life, the Qur'an insists that God is merciless in this regard. Those who die as disbelievers, even if they disbelieved due to such harmless flaws as sincere investigation and honest doubt, will be tormented forever by such tortures as fire, shackles, drinking boiling water, etc. The Qur'an even suggests that God
causes some people to doubt the authenticity of the Holy Qur'an, and then he sends them to hell.
It is possible to be
reasonable, even if you are not very
forgiving, but the God described by the Qur'an is neither. A perfect, wise, merciful God should not be
less forgiving and
less rational than the best human beings, unless of course the Qur'an is man-made, and so the God it describes has some of the defects of its human authors (as well as some of the noble traits of its human authors).