1 Peter 1:15-16
but according to the Holy One, who called you [i.e., God], you people also should become holy [i.e., separated for God's service] in all your conduct,
Matthew 5:48
Therefore, you must [attempt to] be complete, just as your heavenly Father is [already] complete.
2 Corinthians 6:14-16
Do not team up with unbelievers [i.e., in close relationships, such as marriage, etc.]. For what do righteousness and wickedness have in common? Or, what fellowship can light have with darkness?
2 Corinthians 7:1
[So], since we have these promises [See 6:16-18], dear ones, we should purify ourselves from everything that pollutes [our] body and spirit while living lives completely separated [from sin], out of reverence for God.