en_tn/2ti/02/05.md

as an athlete, he is not crowned unless he competes by the rules

Paul is implicitly speaking of Christ's servants as if they were athletes. (See: rc://en/ta/man/translate/figs-explicit and rc://en/ta/man/translate/figs-metaphor)

he is not crowned unless he competes by the rules

This can be stated in active form. Alternate translation: "they will crown him as winner only if he competes by the rules" (See: rc://en/ta/man/translate/figs-activepassive)

he is not crowned

"he does not win the prize." Athletes in Paul's time were crowned with wreaths made from the leaves of plants when they won competitions.

competes by the rules

"competes according to the rules" or "strictly obeys the rules"