First some background on what I see:I'm not a gnostic.
But YOU are always posting scripture,,,so you must know.
If witnessing, should you know? So many questions to answer.
But, to answer,,,,faith is more important.
What I believe is that a real Christian [one who follows or strives to follow] Christ is usually, [always?], a mixture of belief and knowledge with regard to God and the things of God. The problem is that for many or even all of these things we don't know the difference between those things we really know and those we only believe. As we grow toward God, assuming that we are, the balance should be moving in favor of knowledge over belief. This should be the process of little by little , step by step, precept upon precept. It goes along with the words of John the Baptist here:
"He must increase, but I must decrease." John 3:30
And the end result hopefully is understood here:
"Looking unto Jesus the author and finisher of our faith; ..." Heb 12:2
He is the finisher of our faith. When He finished working on and through that faith, then only knowledge would remain.
But now to your question:
So then what to say to someone who is listening to hear from God through me? What was it that Jesus did?
"Believest thou not that I am in the Father, and the Father in me? the words that I speak unto you I speak not of myself: but the Father that dwelleth in me, he doeth the works." John 14:10
What we need to do is continuously eat the flesh [partake of scripture?] so that when the time is on us to speak, the Spirit in us will quicken [bring to Life] the what we have consumed so that it is the Living Word that comes out of our mouth in witness...
Of course, we should know that our witness to people is not found only in the words spoken with our mouths. Our whole appearance to everyone who is watching should be our witness to them even if we never have a one to one conversation. How do we get to the point where we will always being doing exactly what Jesus would be doing if He were in our place?