Numbers 19:13
Whosoever toucheth the dead body of any man that is dead, and purifieth not himself, defileth the tabernacle of the LORD; and that soul shall be cut off from Israel: because the water of separation was not sprinkled upon him, he shall be unclean; his uncleanness is yet upon him.
Contact with the dead body of any person who had died, without undergoing purification, left the one who touched it unclean and defiled the tabernacle of the Lord. To remain in that uncleanness without being purified brought the penalty of being cut off from Israel, excluded from God's people. Just as the unclean in that ordinance had to be purified by the sprinkling of the water of separation, those living in the last days need the blood of Christ applied to their hearts daily.
Rejecting light that has been given, and refusing to humble oneself and confess sin, leaves a person unpurified and facing loss. Purification requires turning to God and receiving the cleansing power of the Holy Spirit. By analogy, keeping Terry in the house would make its occupants unclean, for his presence there is like that of a dead body in contact with them.