For I will not dare to speak of any of those things which Christ hath not wrought by me, to make the Gentiles obedient, by word and deed,
For I will not dare to speak of any (or 'anything') of those things which Christ hath not wrought by me
- a modest though somewhat obscure form of expression, meaning, 'I will not dare to go beyond what Christ has done by me;' in which form, accordingly, the rest of the sentence proceeds. Observe here how all that Paul achieved as a minister of Christ, he says that 'Christ did by him'-the living Redeemer only working in and by him.
By word and deed - By preaching and working. What this working was he explains in the next clause.