I start out with the idea that "Hell Fire" is God present in person in all God's love, beauty and glory that purifies and calls out the best in everyone. Some people will find this heaven, but others who have not wanted the best in them to be in control will find it very, very uncomfortable to be with him. Jesus is their deepest desire, they long to run into his loving arms; but they don't know him. They are unforgiving people and thus cannot comprehend forgiveness. They picture what they would do to someone like themselves if they were God. They want to run to him but refuse to yield to this deepest desire. They want to but won't.
In the end God treats everyone the same, but our choices depend on how we respond. While this comes from Ellen White, I believe that it's Biblical. She pictures us seeing Jesus coming in the clouds and we are overwhelmed and ask "Who shall be able to stand?" There is a moment of horrible silence, then Jesus says [sings?] "My grace is sufficient for you!" To these words we find two responses. Some realize "Yes, this is my friend Jesus and his grace is sufficient for me! This is my God and He will save me!"
Jesus does not say "My grace is sufficient for you Stan and for you Matthew, but sorry Kevin, it's not sufficient for you." Jesus says to each and every one of us "My grace is sufficient for you." Some believe him, others have just had their ear drums vibrate to the sweetest sound it ever heard telling them that his grace is sufficient for them, but they do not believe him. They think he is lying and they run to the rocks...
Heaven is total reality. In a lot of ways hell is the rejection of reality as they become slaves to the figment of their imagination.
Building on this are the three aspects of the trinity, the issues of the great controversy which creatures need to ask if God is who God claims to be or not, and the mystery of how Lucifer instead of looking for the answers to this question, turned the question into three deceptions one against each member of the trinity.
The Holy Spirit works with every heart. Every group/religion has a mixture of truth, error, misunderstandings and superstitions. The monotheistic religions have more truth available to them, especially as they accept the Bible and aspects of the Bible, but many with much truth available don't take advantage of this gift, while many with less available treasure what they have. The Holy Spirit has, and we should have "Listening Love" where we want to understand the other person, encourage them in the truth that they have and encourage them to grow.
Being saved "in the name of Jesus" is not righteousness by vocabulary, but the character of Jesus, even if they are in religions that don't understand the word "J-E-S-U-S". or where he has been misrepresented over the centuries where the word becomes a sore spot and we expect them to just give up centuries of pain and that they are lost because they are uncomfortable saying that word. But they may know HIM, Who he is. Praying in Jesus name means to pray for the same types of things Jesus would pray for. Our Jewish and Muslim friends have an amazing amount of truth, but may not see it, and instead of helping them to see what they already have, we want them to give the correct vocabulary. Jesus cries at this. Historians said that it is not clear how pious Manfred von Richthofen (The Red Baron) was, but his hero was Oswald Boelcke who was very pious and a devote follower of the Lord. Paul said to imitate him as he imitated Christ. Von Richthofen tried to imitate Boelcke's Christlikeness. Very different from others who admired Boelcke's prowess in shooting down enemy planes but not his character. Von Richthofen was more impressed by Boelcke's character than he was by Boelcke's ability to shoot down enemy planes. Von Richthofen was impressed by the way the character of Jesus was reflected in Boelcke. Is this not accepting Jesus?
When I was at Andrews, going through the White Estate vault, I came across a document that I believe that Mrs. White wrote. Since I cannot go back and confirm this I will not say "Mrs. White said..." but I was going through her writings and as far as I know she said this. The document talked about "atheists" and the writer but them into two groups. The one group were "infidels" who were in rebellion against God. The second group was called "Honest doubters" who questioned how God can exist with different issues we face in the world, but they develop caring, kind characters. This writer saw heaven as having room for these "honest doubters."
It's late, so this is a place to start.