Purity as a biblical concept is not defined in reference to sexuality, or non-sexuality. Sexual people (or those who inspire sexual thoughts) are not “impure.”
Hagnizó, ‘purity’, is biblically defined in many situations. In John 11:55 the Jewish people ‘purify’ for Passover. The instructions for that procedure, in Numbers 9:10–12, make no reference to sex.
Instructions on ritual cleansing are frequently given (eg. Gen. 35:2, Exo. 19:10–11, Num. 9:11–12, etc.), and sexual touching, sexual feeling, sexual thinking, is never the problem. The purification is from the effects of other divinities.
A Christian person has a guide for purification in 1 Peter 1:22: “You have purified your souls by obeying the truth in order to show sincere mutual love. So love one another earnestly from a pure heart.”
In the teachings of Jesus, we become “pure” through love.