David Watson, Called & Committed: World-Changing Discipleship, (Harold Shaw Publishers, Wheaton, IL; 1982), pp. 142-143
1. A witness must have a first-hand experience of Christ. Hearsay is not acceptable in a court of law, nor in the court of this world's opinion. People will listen only to what we have personally seen and heard.
2. A witness must be able to express himself verbally. We may witness effectively through our lives, our work, our relationships, our attitudes, our suffering and even our death, yet we must still "be ready at all times to answer anyone who asks you to explain the hope you have in you." We must do so "with gentleness and respect," and with the integrity of our lives demonstrating the truth of our words.
3. A witness will have confidence in the power of God. He relies on the power of the message of Christ and him crucified, and the power of the Holy Spirit. He knows that God can break through any defenses, and change any heart. This confidence will not be brash, but humble and sensitive, marked by much prayer. He knows that without God he can do nothing, but that with God all things are possible.
4. A witness will have compassion for the spiritually lost. He will care for them as individuals who matter deeply to God: made in his image, redeemed by his Son, and to be indwelt by his Spirit.