Another great question, son.
We have touched on this question before. Refer to…
Perhaps it is best to start with who is forgivable: fornicators, idolaters, adulterers, effeminate, homosexuals, thieves, the covetous, drunkards, revilers, and swindlers to name a few. All things are lawful but not all things are profitable. This seems like little help.
Perhaps we should consider what rules are required. However, even in the law, God cursed the people for loosing God in the rules warning them…
So then, the word of the Lord to them will become: Do and do, do and do, rule on rule, rule on rule; a little here, a little there so that they will go and fall backward, be injured and snared and captured.
What about knowledge? Perhaps we must know the name of God. Unfortunately, no man knows the heavenly name of God. Even when Moses asked him His name, the response “I AM who I AM” seems more of a truth statement than a name. Even rejecting Jesus in the flesh is forgivable.
The one requirement is the spirit of God. If the spirit of God lives in anyone, he is truly alive. If the spirit is not present, he is walking dead. The problem is that man is not in control of such a relationship. God alone can bestow it after searching our heart.
In the end, I cannot answer this question. I am not the final judge. However, know that God is searching the hearts of all men. He longs to gather all men to himself; however, he ultimately bestows mercy on those whom he ultimately chooses.