Leviticus 13:55
And the priest shall examine the diseased thing after it has been washed. And if the appearance of the diseased area has not changed, though the disease has not spread, it is unclean. You shall burn it in the fire, whether the rot is on the back or on the front.
Ezekiel 24:13
On account of your unclean lewdness, because I would have cleansed you and you were not cleansed from your uncleanness, you shall not be cleansed anymore till I have satisfied my fury upon you.
Hebrews 6:4-8
For it is impossible, in the case of those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit,
2 Peter 1:9
For whoever lacks these qualities is so nearsighted that he is blind, having forgotten that he was cleansed from his former sins.
2 Peter 2:20-22
For if, after they have escaped the defilements of the world through the knowledge of our Lord and Savior Jesus Christ, they are again entangled in them and overcome, the last state has become worse for them than the first.