The early church faced enemies from without and even within. Paul instructed believers to stand firm and not compromise. He had previously exhorted them to follow Christ and so they understood what he meant when he now instructs them to imitate him.
They, like us, are encouraged to fight against weakness and worldliness knowing God knows the heart and we cannot fool God. There is a difference between professing Christ and confessing Christ. What a sin to pierce Christ while portraying to be His friend. Sadly wolves are in both the pew and the pulpit in churches today.