let me explain what I think from my studies , I am taking several trains of thought and wrapping them together. I take the work of Micheal Heiser and his book Unseen Realm and combining it with the idea of Apokatastasis ( Acts 3:21) and combine them to get what I think is a better understanding of what the Father has done , is doing, and will do. If you understand that God works in ages then we see from scripture that from Adam till Moses for a person to walk and serve God you did not have to place your faith in Jesus you only followed what God has said ( that part was not preserved for us to know) but God had a way of sorting out those who were following Him and those who were not. Those who followed Him were given the promise of a heavenly home away from the curse of this world. Then Moses came with the Law and now to follow God you followed the Law, those who did were promised a " promise land and a new city that God would make for them. Then came Jesus and now according to Him those who follow him are filled with his Holy Spirit , He no longer calls us slaves but brothers , and we will reign and rule with him on his throne. That is why the bar that Jesus set is higher , example before you were told don't kill but now I say that if you have hate in your heart toward someone you are guilty of murder, same with adultery ect. The bar has been raised because its not a heaven or hell choice its a are you going to be part of Jesus family and reign and rule with him, become elohim , or are you going to be the ones who are the subjects of that rule and reign. I believe Hebrews when it says that the blood of bulls and goats never took sin away, and that when Jesus said no one comes to the Father but through me that was a truth for all the ages , so all those from Adam till Jesus that followed God had to trust in Jesus in order to get to the promise that they were given , which if true ( and it has to be otherwise there are multiple ways to the Father) means that post mortal death acceptance of Jesus has been done before and why would not God stay with that pattern. So all who are to be residents of heaven must put their trust in Jesus , but for us who do it in the mortal body we get the added bonus of becoming part of his family, again that is why the bar was raised.
That is why Jesus said if you deny me before men I will deny you before the Father, only those who die to self and pick up their cross and follow Jesus have the right to become part of the family and will rule and reign with Jesus , we are residents of heaven but also part of Jesus family something that was not offered to any other age, So for me I differ from what most UR people believe I do not believe that all go to heaven, I see that is a offer made to you while in the mortal body , but I believe that if Rev 22:14-15 are somewhat literal those who are outside the New Jerusalem and are not aloud to go in are those who trusted in Jesus post mortem by way of the lake of fire , they live on New Earth, restored to Garden of Eden, for all the ages just like Adam would have if he had not sinned, a reset is what I see scripture pointing to. This is just a condensed version that would take a book to flesh out.