How frequently the servants of God have had to say this! John uses almost the same words at the beginning of I John 1: "Look, our hands have handled Him. We have looked at Him with our eyes and heard Him with our ears." Who is the we? He speaks of the apostles, intimating, "Get back to what we taught you." Jude and Peter say the same thing.
These men were not confronting the same people, but they probably were confronting elements of the same philosophical system that affected the church so strongly even as early as the AD 50s and 60s. Human nature always has a strong drive to make the way of God more attractive to the senses by blending it with traditions that are not part of God's Word.
This is what is found in Exodus 32, which God included in His Word so that we would see it etched vividly. The Israelites tried to introduce the Egyptian religion they had just left into the way of God. They used the bull to represent the nature of God. No wonder God was so upset! They were trying to syncretize paganism with the truth of God, just a few chapters after He gave them the terms of the Old Covenant. The Old Covenant was signed, sealed, and delivered in Exodus 24, which was a very short time chronologically - and they were already trying to twist the nature of God into something radically different.
We see elements of this in the book of Colossians. The theological term for this is, as has been already mentioned, syncretism. It means "a joining, a meshing, or a blending together," "an alloying." Is anything purer than the Word of God? How could a person think to improve it by adding something foreign?
The outstanding historical example of syncretism (at least in terms of what we call "the Christian religion") is Catholicism. It is a universal religion precisely because it has absorbed traditions of worship from cultures all over the world. Its Protestant daughters, having come from the same system, have not rid themselves of most of the sycretic beliefs, having thrown off only the governance of the Pope and several of the more blatant pagan practices.