“That their hearts might be comforted, being knit together in love, and unto all riches of the full assurance of understanding, to the acknowledgement of the mystery of God, and of the Father, and of Christ;”
King James Version (KJV)
2:2 Unto all riches of the full assurance of understanding, unto the acknowledgment of the mystery of God - That is, unto the fullest and clearest understanding and knowledge of the gospel.
Col 2:2 That their hearts. He was deeply anxious that they might "be comforted, . . . knit together in love", and enjoy the full assurance of understanding, a clear insight that would lead them to know the mystery of God. This knowledge would make them proof against the arts of false teachers. For "mystery", see notes on Col 1:26,27.