Sex is also to be engaged in Krsna consciousness. The conception of God as a father or mother does not allow the engagement of one’s sex in the service of the Lord because there is no sexual relationship with the father and mother.

But in the conception of God as a lover, there is sexual engagement also. Therefore, Caitanya Mahaprabhu gave the most perfect information of our engagement with the Supreme Lord. In other religious conceptions of life, God is at the utmost taken as the father or mother. Many worshipers in India take goddess Kali to be the representation of God. Of course, that is not sanctioned, but the belief is there, and also in the Christian religion the conception of God is as a father. But Caitanya Mahaprabhu informs us that one can even have sexual engagement with the Lord. This information is Caitanya Mahaprabhu’s unique contribution. In this material world, sexual engagement is considered to be the highest engagement, the greatest pleasure, although it exists only in a perverted form. No one, however, has conceived that there can be sexual engagement in the spiritual world. There is not a single instance of such theology anywhere in the entire world. This information is given for the first time by Caitanya Mahaprabhu: one can have the Supreme Personality of Godhead as one’s husband, as one’s lover. This is possible in the worship of Radha and Krsna, but no one, especially the impersonalists, can understand Radha-Krsna. The impersonalists have no idea; they cannot even conceive that God has form. But Caitanya Mahaprabhu says that not only does God have form, but He has sex life also. This is the highest contribution of Caitanya Mahaprabhu.

From “The Science of Self-realization” by Srila Prabhupada