Is it obligatory to gradually accustom oneself to performing the prayer for one who has never prayed before, or to begin performing all five prayers at once in the mosque, knowing that previous attempts to commit all at once have failed?

Prayer is the pillar of faith, and whoever abandons it is in grave danger. Denying its obligation is an act of disbelief by consensus. Regular performance of prayer is an immediate obligation without procrastination, as procrastination is from Satan to deter one from prayer. There is no excuse for abandoning it under the pretext of gradual habituation, for the five daily prayers are not a strenuous act, and what is required is sincere determination. If the choice is between gradual commitment to prayer or abandoning it entirely, then gradual commitment is preferable.