In Acts 20:17-38, Paul passed the torch of ministry to the elders of the church in Ephesus. In his speech to them, Paul described the character of elders and their work of ministry. With a few such elders as Paul described, the church has the team it needs to fulfill the mission that God has given it.
It is hard to imagine what the world would be like without Saul of Tarsus (the apostle Paul), but it would have been harder...
No matter how long we have been Christians, we can always keep growing more and more in purity and love.
God fulfills his plan against human opposition and even through human suffering.