Separate Holy From Unholy!
Why is it so important that holy things be separated from unholy things? Because God is holy and has called believers to be a holy people set apart for Himself. Peter tells us that we are a holy nation, a royal priesthood, and a people who have been called out of darkness into God’s marvelous light. God desires that the world would see the zealous good works of His holy people and glorify Him because of them. This is why it is so critical that we abstain from fleshly lusts, which war against the soul and dilute our influence and impact on the world. (See I Peter 2:9–12 and Titus 2:12–14.)
Being effective salt and light in the world requires that we have an inward separation from that which is unholy.