In wrapping his letter to the church of Corinth, Paul tells them to be watchful (or to stay on their guard) along with the command to stand firm in the faith. This goes beyond just standing firm in the Christian faith, but standing firm in sound doctrine (Phil. 1:27; 1 Tim. 6:21; Jude 3). In the previous chapter, Paul was teaching about their faith in the resurrection of Jesus and the resurrection of all who follow Him. Some had watered down their belief in the resurrection, yet Paul reminded them that the resurrection was absolutely essential to the gospel in which they stood (1 Corinthians 15:1).
Paul tells us that it is our duty to look out for any kind of false teaching (i.e. prosperity gospel, legalism, antinomianism, cults disguised as Christian denominations, etc.). He also tells us to have courage and to be strong. It is our faith in Christ that will face opposition from our culture and from those around us. We need to prepare for this and resolve to remain strong in our faith with strength and courage.
