en_tn/rom/15/18.md

I will not dare to speak of anything except what Christ has accomplished

This double negative emphasizes that what Christ has accomplished is the only thing that Paul wants to speak about. Alternate translation: "I will dare to speak only of what Christ has accomplished" (See: rc://en/ta/man/translate/figs-doublenegatives)

for the obedience of the Gentiles

"so that the Gentiles will obey God"

These are things done by word and action

This can be translated in active form: Alternative translation: Alternate translation: "These are things that Christ has accomplished through what I have said and done" (See: rc://en/ta/man/translate/figs-activepassive)