Summary: The believer’s future is connected with Christ’s. Christ is the faithful Son and is the Father’s rightful heir. The Christian by means of his adoption is a joint heir with Christ and may look forward to eternal glory in the presence of the Son (cp. John 1
For as we share abundantly in Christ’s sufferings, so through Christ we share abundantly in comfort too (2 Corinthians 1.5).
Those who are led by the Spirit of God are children of God; they have received the Spirit of adoption whereby they approach God as “Abba! Father!” Their adoption is sealed by the reception of the Holy Spirit who guarantees their filial relationship with God: In him you also, when you heard the word of truth, the gospel of your salvation, and believed in him, were sealed with the promised Holy Spirit, who is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory (Ephesians 1.13-14). The believer’s future is connected with Christ’s. Christ is the faithful Son and is the Father’s rightful heir. The Christian by means of his adoption is a joint heir with Christ and may look forward to eternal glory in the presence of the Son (cp. John 14.3). However, Paul links this future glory with a present suffering.
The theme of suffering is not a tangential issue for Paul. It is connected to his gospel at several points. First, the passion of Christ (Christ’s suffering on the cross and the events that led up to it) is at the heart of the good news: For while we were still weak, at the right time Christ died for the ungodly (Romans 5.6); also, For our sake he [God] made him [Christ] to be sin who knew no sin, so that in him [Christ] we might become the righteousness of God (2 Corinthians 5.21; Philippians 2.8; cp. Luke 9.22; 22.15; 24.26). Second, Paul recognized that Jesus’ message about the kingdom included the willingness to suffer: And he [Jesus] said to all, “If anyone would come after me, let him deny himself and take up his cross daily and follow me. For whoever would save his life will lose it, but whoever loses his life for my sake will save it (Luke 9.23-24; cp. 9.57-62; Matthew 5.11-12). Accordingly, Paul’s letters frequently refer to the believer’s suffering: For it has been granted to you that for the sake of Christ you should not only believe in him but also suffer for his sake, engaged in the same conflict that you saw I had and now hear that I still have (Philippians 1.29-30; cp. 2 Timothy 1.8-12). Finally, Paul’s appointment to the apostolic ministry was included the destiny of personal suffering. As you may recall from Luke’s account of Paul’s conversion, Ananias initially resisted the Spirit’s prompting to pray for the restoration of Paul’s eyesight because Paul had a reputation for persecuting Christians. However, the Lord persisted and said to him: “Go, for he is a chosen instrument of mine to carry my name before the Gentiles and kings and the children of Israel. For I will show him how much he must suffer for the sake of my name (Acts 9.15-16). Paul came to understand that a willingness to suffer for the gospel was central to its proclamation (cp. Colossians 1.24-29).
Suffering was not a side effect of the Pauline mission; rather it was at the very center of his apostolic evangelism. His distress validated and legitimated his message, demonstrating the truth of the gospel. This is not to say that sufferings in and of themselves ratify the truth of the Pauline gospel. Rather, Paul’s sufferings provide evidence of the truth of his gospel. Indeed, his sufferings are a corollary of the sufferings of Jesus. (Thomas Schreiner, Paul Apostle of God’s Glory in Christ, p. 87)