We have promises from God which encourage us to cleanse ourselves of anything that would come between us and our relationship with God. Imagine giving all you had to give to your children and asking them to protect your gift and not anything in their life interfere.

Paul encourages his hearers to cleanse themselves of anything that would or could get in the way of the fullness of the relationship he wants with us.

This may seem a like a lot to ask, but with the help of the Holy Spirit our hearts can be changed and transformed.  If we delight in the Lord He will give us the desires of our heart, which in this case is Holiness...