Paul alluded to the afterlife in 2 Corinthians 4:16-18 so it’s natural that he develops this more in 5:1ff. It’s an encouraging section of Scripture as the apostle speaks of what God has planned for His people and his personal desire to enter into that. “So that what is mortal may be swallowed up by life” (v. 4) is a powerful statement as is v. 5, which functions as sort of a summary statement—“Now the One who has fashioned us for this very purpose is God, who has given us the Spirit as a deposit, guaranteeing what is to come.” God made us to be with Him for eternity and His Spirit in us is a down payment on what is to come. All of this makes Paul “confident” and assured in regard to the future (v. 6, 8). He looks forward to being with God and would “prefer” it to his current state (v. 8). The ”so” of v. 9 follows on the heels of this and seems to suggest something to the effect that because Paul would prefer to be with God he naturally wanted to be pleasing to Him.

Paul adds another reason for pleasing God in v. 10 when he says, “For we must all appear before the judgment seat of Christ, so that each of us may receive what is due us for the things done while in the body, whether good or bad.” He was conscious of the truth that he could be “disqualified for the prize” (1 Corinthians 9:27) and he wanted the Corinthians to understand that possibility for themselves. The follower of Jesus can be confident in regard to Judgment (read 1 John). The person who has decided not to follow Jesus faces wrath. Both of these are clear. There is a third category: disciples who live on the margins with seemingly one foot in and one foot out. It seems as though some of the Corinthians belonged in this category. But it wasn’t because of sin in their life—it was because of their negligence in dealing with sin that placed them in jeopardy. Paul will tell them to examine themselves to see if they were in the faith (2 Corinthians 13:5). Some of them needed to be “reconciled to God” (5:20). He wanted them to understand that their faith was serious business and it must be reflected in their life. If they disowned Jesus through a rebellious lifestyle then He would disown them at the judgment (2 Timothy 2:11-13).
It’s difficult to be balanced in our thinking about judgment. Some treat it as if they’ll be having a cup of coffee with the Almighty while others live in constant anxiety about it. Neither of these reflects the biblical witness. There’s also a good bit of honest confusion about the subject. If we have all of these texts speaking of the atoning work of Jesus and our appropriation of that by faith (and we most certainly do)—then what is there to judge? After all, didn’t John tell people he was writing they had eternal life (1 John 5:13).
All that is gloriously true and there is wonderful assurance for the follower of Jesus but none of that precludes the idea of judgment. Eternal life is simply sharing in the very life of God. We are able to do that by grace through faith. If we stop allowing faith to be a part of our life, we stop sharing in His life! It isn’t a question of whether God is powerful enough to keep people saved (of course He is!). The issue is free will. God will coerce no one into believing or to continue believing. It’s His desire that we choose. And followers of Jesus can decide to “unfollow.” Demas did just that (2 Timothy 4:9-10). So did some of the disciples in Galatia (Galatians 5:2-4).
Our relationship with God (like all other relationships) is dynamic and ongoing. (That’s why Scripture speaks of salvation in the past, present and future tenses). It is most like the marriage relationship and is often spoken of that way (See the prophets, Ephesians 5 and other texts). How do you determine if someone has been faithful to their marriage vows? It is not simply if they remained married. Sadly, there are many instances of marriages that exist in name only. Two people share a roof and nothing else. You determine if someone has been faithful to their vows by looking at their attitudes and actions over the course of their marriage to see if they reflected the promises they made. Judgement is no different. Did we live a life that reflected our profession of Jesus as Lord? The standard isn’t perfection or sinlessness, but faithfulness. Did we walk in the light? That’s what judgment will be about.
Having said that, there’s more that needs to be said.