Let no one keep defrauding you of your prize by delighting in self-abasement and the worship of the angels, taking his stand on visions he has seen, inflated without cause by his fleshly mind, [Colossians 2:18]
It seemed that some members of the Colossian church were worshipping angels as a show of humility that they were not worthy to come directly before Jesus. Paul regarded that as false humility. They probably did not realise that by doing so, they were taking away the honour that was due to Jesus, and in a way disclaiming Jesus.
Jesus is the only mediator between man and God.