From Greg Bahnsen's book Always Ready:
God must give us the success in our apologetic endeavors. Thus we must "walk in wisdom toward them on the outside" (Col. 4:5), not argue from foolish presuppositions of unbelief but according to the presupposed authority and truth of God's wise revelation in the gospel. When we do this we will know how to answer every man (v.6), looking to God in continuing prayer that He might grant apologetical success by opening a door for the word (vv. 2-3). The corrupt communication which characterizes humanistic thought (cf. Matt. 7:17-18) must not proceed from our mouths, but rather good works which represent the mind of God (cf. Matt. 19:17) and can minister grace to our hearers (Eph. 4:29). As Paul, our speech must not be with enticing words of human wisdom but with the powerful proof (demonstration) of the Spirit (I Cor. 2:4), knowing that the faith of our opponents must stand in the power of God and not the wisdom of men (v.5). Such faith is unto understanding. Consequently, the apologist must work from the presupposed word of Christ, be in constant prayer, and look to God for the door to be opened to the word (cf. Acts 14:27; 1 Cor. 16:19; 2 Cor 2:12) and for the granting of wisdom, genuine knowledge, and the enlightenment (cf. Eph. 1:16-17).