What about those who don’t think God is real?
God is both more truly just AND more truly merciful than any human being (yourself included) could ever dream of being. He surely knows that some, through no fault of their own, don’t think He is real, and does not punish those for something that isn’t their doing or fault.
You can be sure God would never permit someone to be damned without their understanding what they’ve done wrong and how exactly their eternal fate is both perfectly just AND perfectly merciful in the circumstances.
Wouldn’t someone who rejects God while deep down knowing better (as full knowledge is a condition that is required before a sin is mortal) WANT not to be in His presence? Just like an addict who is deep in the throes of their addiction would often rather cling to the false and temporary sense of wellbeing that indulging their addiction gives than face the truth and get sober?
Remember - in addition to all the conditions that must accompany a sin for it to be mortal - it must be grave matter AND be committed with both full knowledge AND full consent - there is a further condition, which is that of final impenitence. Not only must the sinner consciously and freely choose to commit mortal sin, but they must maintain an attitude of impenitence - not being sorry for that mortal sin - right up to the point of death. How many good Christians do you honestly know who would not only sin mortally but remain impenitent about it WHILE really knowing deep down that what they’ve done is wrong?
Such a truly hardened soul, you can be sure, wouldn’t repent even if shown Hell itself. That’s where your viewpoint is wrong. God isn’t looking to lock anyone out of heaven, quite the opposite - He’s giving them every help He can to attain salvation for all, and allowing every indulgence He can possibly offer in regard the offences we commit against Him.
He offers us His own self in the person of His only son - to redeem us. What more could He possibly do to prevent our damnation, seriously, if His own death isn’t enough? What more could possibly motivate us to obey Him and seek His presence in heaven if His passion and death can’t?
What was Christ’s prayer in Gethsemane? “If it be possible, let this cup of suffering pass me by”. In other words “if you can save people by some other, better means, other than the Passion that awaits me, please do.” This wasn’t just a selfish desire to personally avoid suffering - Christ was never selfish. Surely He also wanted to be sure that what transpired was in fact the best POSSIBLE method of achieving salvation for people.
Clearly, as the Father’s answer indicates, it was and is. Why, then, do you think there’s anything more or different that God could or should do that would achieve a better result - save more people, spare more of their suffering?