Philippians 3:18-19 KJV
(For many walk, of whom I have told you often, and now tell you even weeping, that they are the enemies of the cross of Christ:
Whose end is destruction, whose God is their belly, and whose glory is in their shame, who mind earthly things.)
The Apostle believed it to be proper to tell those he loved about, and to warn them about, professing Christians who are enemies of the cross. Various commentaries confirm that he is referencing believers and suggest they are Judaizers. If this is so, their tactic is employed even today by those who take a gospel ministry and pervert it. They do not create a work of their own; they are only able to ruin one that has been created. The key to the passage is that Paul, though weeping, kept warning those who would listen about professing Christians who become enemies of the Cross through compromise with the world.
I know what it is like to weep over loved ones who have become enemies of the Cross through worldliness. Not that they have quit their profession of faith, or even their work of ministry, but that they have so compromised it with worldliness that it is no longer a work of the Lord. It is not a grief that may be gotten over. I weep as I warn others about it again and again. Years now have gone by and the tears are as fresh today as they were in the beginning of the perversion. I cannot quit weeping over it because I cannot stop telling others and warning them.
As children of God we must take note of those who walk the way we were originally taught, and follow them carefully, because there are many who would love to take the people of God and lead them down a path of compromise and worldliness.