1 John 1:6

1:6 This is the first of several instances in which John challenges the claims of the Gnostics, who had broken away from the apostolic fellowship and were thus living in spiritual darkness. They claimed to have fellowship with God but did not express his character, which is light. Jesus had warned the Jewish leaders of his day not to let the light they thought they had be darkness (Matt 6:23)—their religious beliefs had blinded them to the spiritual illumination they could have received from Christ. In like manner, these Gnostic teachers thought they were enlightened but were actually darkened by their so-called illuminations. They claimed to have spiritual experiences from God, yet they rejected fellowship with the ones who had actually seen God in the flesh, namely, John and the other apostles.