Matthew 26:21 (NASB)
Truly I say to you that one of you will betray Me.
If we are to be real with God, we have to be real with ourselves first. Here was Jesus having a pleasant passover meal when He suddenly tells His disciples that one of them will betray Him. That's how God speaks to us, suddenly and unexpectedly. We shouldn't shoo Him away just because the Holy Spirit has told us something about ourselves that we don't like. God knows us better than we know ourselves. We simply have to repent of the possibility of such sin within us and let Him cleanse us.