A true believer will be known by his fruits, or godly character. Notice verses 21-23 . It is not everyone who calls to the Lord will be saved, but those who do the will of Jesus Christ's Father. Many will claim to have done miraculous things, but Jesus will reject them as workers of evil. They will bring in destructive heresies, one of them being to deny Jesus.
Covetousness means 'the wish to have more'.
Jesus Christ is the Christian's leader we need to look to. He didn't make money from his followers. He was poor. Check them out. We are not infallible.