Asceticism is the overly zealous practice of disciplines with the hope of pleasing God by extreme forms of self-denial. The Bible teaches both discipline and self-denial. IF we are servants of Christ, there are demands on our lives that cannot be ignored. We are called to holiness. That holiness will include sexual purity, clean speech, a recognition of God's right to first place in every moment.
Asceticism takes holy living and corrupts it.
The ascetic starts to trust his own actions of self-denial as proof of his faith more than he does Christ. Bev and I know a dear Christian couple who are now well into their old age. Somewhere in their pilgrimage, they developed the idea the sexual purity means no sex except for those times in life when a couple is ready to conceive a child. Down through history the church has been plagued with rule-makers who take the important guidelines of the Word for holy living and twist them into laws by which others are judged. In my youth, I attended a church where the LAW was thundered from the pulpit regularly.