Serving God Out of Envy

Philippians 1:15-16 Some indeed preach Christ even from envy and strife, and some also from goodwill:
The former preach Christ from selfish ambition, not sincerely, supposing to add affliction to my chains;

It's hard to believe that some Christians hated Paul so much that they preached Christ. Since their motive was selfish ambition, it appears that their goal was to build their own influence. Why were they in Christian work in the first place?

A Christian who wants to serve God wants a good thing. He may also be responding to grace, which gives us the desire and ability to do God's work. But then, failing to accept God's grace, he becomes bitter at someone else who has a bigger ministry.

The warning here for the saints is to turn away from envy, seeing how much harm it can do to you.