Universalism is a dangerous doctrine.
All the focus is on - Jesus saving everyone at the end. Doesn't matter what kind of life a person lived. Doesn't matter if they worshiped idols, or anything like that. Doesn't matter if they ever believed there was a God that was mighty than them. Jesus is just gonna save everyone in the end. Now, while I believe in Universal salvation (Jesus saved everyone since his victory - from Satan, his angels, death, hades, the wrath of God that came on Jerusalem, and of course sin has been paid for (it was paid for already) There is no such thing as "All way lead to heaven" which is basically what universalism is.There is only one way to heaven, that is through Christ Jesus. He is the truth, the way, the life and no one gets to the Father except through Him.
While I do believe the Lake of fire still exist it comes from God, and John the beloved - states there are people on the outside of the heavenly CITY. The city gates never close but the damage is done after this life of resurrection, without Christ. There is only the resurrection of condemnation - with a spiritual body not equipped to dwell in the light - they live outside of the Kingdom. This is good to at least know, that God doesn't destroy them because he desires none to perish - however he does get rid of everything of the prior age mentioned in the second note of (salvation).
The only way to receive deliverance is to come to Christ and die, be buried, and raise with Him being born again in newness of life. So everyone is saved from - Jesus saved everyone since his victory - from Satan, his angels, death, hades, the wrath of God that came on Jerusalem, and Sin has been paid for. Salvation to be delivered from darkness to light, and to be saved to (notice the difference) (From - To) - the Kingdom of God is to come to know the Lord Jesus Christ, and the one whom he had sent which is eternal life, and to believe on them.
There is no "all ways lead to heaven" which is Universalism which says - all are going straight into the Kingdom of God.
I do believe people will come to know Christ in the afterlife but the damage they did to themselves is permanent, and coming through the lake of fire - perhaps it gets rid of all the darkness and what little is left of them remains compared to those who choose to have faith and build spiritual treasures in heaven, following Christ. Those in the darkness, have to make the choice to come and walk towards God going through "the fire and flames" - does it burn like normal fire? IDK but it will be tough to deny oneself to get through. Reconciliationism. God is good. He has a purpose but it's not like some think, especially in the realm of "universalism."
Why are faithless people claimed to be outside of the gates of the city in heaven?