That is just nonsense. Fasting, prayer, worship, study of the Word, etc. are Christian practices of those who already have the righteousness of God imputed to them. They are all a part of sanctification.
You're actually agreeing with me. I am not criticizing prayer, worship, study of the Word, etc. - not at all - but they are not the righteousness of God, which is what you are saying. I have some unease over fasting as a part of sanctification, though if some folk find it beneficial, I will not criticize. It does seem to me that fasting, even in the O.T. was something done at certain critical times (cf. Ezra 8:21-23; Esther 4:16). I think it is also worth reading Isaiah 58 and check out one's motivation for fasting.
When we have done all these things, we are still 'unprofitable servants.' We do not earn bonus points from God by doing them.
From the Heidleberg Catechism, 1563:
Q1. What is thine only comfort in life and death?
Ans. That both in body and soul whether I live or die, I am not my own, but belong wholly unto my faithful Lord and Saviour Jesus Christ, who by His precious blood most fully satisfying for all my sins, hath delivered me from all the power of the devil, and to preserve me, that without the will of my heavenly Father, not so much as a hair may fall from my head, yea, all things must serve for my safety. Wherefore by His Spirit also He assureth me of everlasting life, and maketh me ready and pre[ared that henceforth I mau live to Him.
Q2. How many things are necessary for thee to know, that thou enjoying His comfort mayest live and die happily?
Ans. Three. The first, what is the greatness of my sin and misery. The second, how I am delivered from all sin and misery. The third, what thanks I owe unto God for this delivery.