It would seem that God could convey both the message of what Jesus has done and the faith that believes it without involving us at all. Dreams, tests, miracles could all be used to the exclusion of personal witness. While I know that God does use these things, it seems to be His strong preference to pull His people into the process somewhere along the line. For some reason, God wants us there.
On the flip side, it can sometimes seem that the conveyance of faith from one person to the next and from one generation to the next is simply an educational process. In other words, we believe because somebody taught us to believe. The Bible clearly refutes this in many passages.
The man without the Spirit does not accept the things that come from the Spirit of God, for they are foolishness to him, and he cannot understand them, because they are spiritually discerned. 1 Corinthians 2:14 (among others)
So what are we doing when we speak to others about Christ? We share the facts of the story and the promises, we quote the Word of God, we even may reason against objections to the Gospel. We treat it as an intellectual process, but it is ultimately a spiritual process that gets through to a person. The Holy Spirit must work with us and through us. In the end, “Let him who boasts boast in the Lord”.
There are many reasons why I want opportunities to talk about Jesus with people: I want to fulfill my God-given purpose, I care about whether somebody has eternal life or not, and so on. One motivation I rarely acknowledge is that when you experience the Holy Spirit working in your words or action it is tremendously exciting– real high.
I can’t make a believer–not by reasoning, threat, promise, bribe, pleading or anything else. But I can share God’s message and become a vehicle for the Spirit to do His work, and so can you.