What does Acts 14:22 mean?

Paul and Barnabas are making their way back home to Syrian Antioch. From Derbe, they could have crossed the Tarsus mountain range and taken a short boat ride. Instead, they backtrack through the cities where they have established churches to give more instruction and select leaders (Acts 14:23).

The locals in Pisidian Antioch had run the pair out of town (Acts 13:50). In Iconium, a mob almost stoned them (Acts 14:5–6). In Lystra, they did stone Paul, leaving him for dead (Acts 14:19). Jesus had warned Paul that he would suffer for Christ's name (Acts 9:16). Later, Paul will say, "I rejoice in my sufferings for your sake, and in my flesh I am filling up what is lacking in Christ's afflictions for the sake of his body, that is, the church" (Colossians 1:24). Jesus' suffering on the cross is all the work we need for salvation; Paul's suffering is necessary to spread the message of salvation to those who need it.

So, when Paul and Barnabas warn the new Jesus-followers that they will suffer, they can speak from experience. Today, Jesus-followers don't always suffer for their faith; some nations and circumstances are tolerant or even supportive of Christianity. Still, Paul knows that those who suffer for Christ will be glorified with him (Romans 8:17), and the believers of the early church did suffer greatly, both in degree and variety (James 1:2) for their faith.

The "kingdom of God" (sometimes "kingdom of Heaven") is any place or situation where God's majesty and sovereignty is present. When the members of the early church suffered, the Holy Spirit gave them strength, resolve, and hope of eternity with God. Stephen literally experienced Paul's promise when he saw a vision of Jesus standing at God's right hand while the mob stoned him (Acts 7:54–60). Prior to his own conversion, Paul witnessed Stephen's murder, and approved (Acts 8:1–3). It's possible that experience influences his teaching to these new believers, many of whom, like Paul himself, will also be martyred for Christ.