It is clear that acceptance of Jesus as our Savior is the only prerequisite for eternal salvation. All believers are ‘equally saved’ and there is no degree of salvation. Is it not true however, that there are rewards (crowns) in heaven based on works, with the right motivation of serving Christ and giving Him the glory of course? Could it be then, that there could also be less or more severe punishments in eternal damnation?
On the surface, what you’re saying seems to make sense, with each group receiving the opposite of the other. Believers receive an eternity of blissful life with God, while unbelievers receive an eternity of punishment without Him. And if some believers will get additional rewards for exemplary service during their lives, it seems logical that some unbelievers would receive more extreme punishment for the depravity of their lives.
But there are some additional factors to consider. First, while the Bible does describe extra rewards for some believers (1 Cor. 3:10-15) it does not mention harsher punishment for some unbelievers. And second, these extra rewards are only spoken of in connection with the Church. There’s no indication that either Old Testament believers or tribulation believers will receive similar rewards. In short, I think the Bema seat rewards might be one more way in which God will demonstrate to the coming ages the incomparable riches of His grace expressed in His kindness to us in Christ Jesus (Ephes. 2:7).