Anyone who thinks that Calvinism is somehow antithetical to prayer simply has not read Calvin. They certainly have not read what he has written about the subject of prayer.
Chapter XX (approximately 70 pages long) of his Institutes of the Christian Religion is all focused on the great subject of prayer as a means of grace. In the opening pages of this chapter, he writes:
“Words fail to explain how necessary prayer is, and in how many ways the exercise of prayer is profitable.” (Vol.2, p.851)
So Calvin not only believed in the necessity of prayer, but he practically didn’t know where to begin to explain just how necessary and how helpful it is to us as believers in Jesus Christ!