The ideal "religion" for a poker player.

[The once and future king]

Buddhism.

Why. It requires no leaps of faith as there is no God or Soul in Buddhism. Also Buddhism is fundamentaly about practise or meditation.

There is nothing better for the poker mind than meditation.

The goal of practise is equanimity, if you have through practise established a good grounding in equanimity then poker with its fluctuations ups and downs and horrible bad beats just washes over the mind leaving it unruffled and able to carry on making the right decisions.

Meditaion also results in much better situational awareness.

In short Buddhism is +EV.