" After hearing some difficult and challenging teaching from Him, many of Jesus’ so-called disciples “withdrew, and were not walking with Him anymore” (John 6:66). By so doing, they gave evidence that they had never truly been His disciples. Perseverance is the hallmark of the true saint. "

― John F. MacArthur Jr. , Colossians and Philemon: New Testament Commentary (MacArthur New Testament Commentary Serie)