Willis, I don't get what the problem is. For starters, what exactly did this other guy say?
- He said, "One can witness without QUOTING Scripture."
- He said, "One can witness without USING Scripture."
- He said, "One can witness with USING Scripture," but by this he meant directly quoting Scripture.
If he said #1, I agree with the guy. God word does not come only in Scriptural form, but also in the form of preaching that is not word-for-word Scripture and might not always contain that element. Often it will be wise to draw directly on Scripture when explaining the gospel, but direct Scripture quotation is not a magic spell that must be uttered to unleash God's saving power.
If he said #2, I agree you are right in the sense that anytime we speak the truth about Christ we are using the revelation of Scripture, which is behind what we say. It isn't something I would spend a lot of time arguing about, but you sound right.
If he said #3, it sounds like you are debating word usage or talking past each other. I suppose you could argue that he should be more precise and avoid a broad word like "using" when he means "quoting," but is that really something to get into a debate over?