And I, brethren, when I came to you, did not come with excellence of speech or of wisdom declaring to you the testimony of God. 2 For I determined not to know anything among you except Jesus Christ and Him crucified. 3 I was with you in weakness, in fear, and in much trembling. 4 And my speech and my preaching were not with persuasive words of human wisdom, but in demonstration of the Spirit and of power, 5 that your faith should not be in the wisdom of men but in the power of God. 1 Corinthians 2:1-5 NKJV 

Confidence to teach, preach, to minister or just to share your testimony with another must not be based on human ability, public speaking skills, enticing and flowery words, but rather on the Holy Ghost helping you. Now, having the power of the Holy Ghost isn’t an excuse not to pray, study, and prepare. In fact, for effective ministry, you’ll need to study (2 Tim. 2:15) and rely on the work of the Holy Ghost (Acts 1:8).

According to Apostle Paul, as mentioned in our text, the one thing that is indispensible when it comes to any expression of ministry a demonstration of the power of God. It isn’t about eloquence, superior wisdom, wise and persuasive words; the message and ministry—whether preaching or teaching—must be centered in a demonstration (manifestation, Greek)) of the Spirit’s power, so that the faith of those receiving ministry might rest, not on man’s wisdom, but rather on God’s power.

The ultimate example of one demonstrating the power of God is seen in the ministry of Jesus. In His time here on earth, Jesus’ ministry was a ministry of power. He manifested astonishing powerful preaching and teaching (Mark 1:14-15, 21-22) and a powerful three-fold ministry that was characterized by teaching, preaching, and healing (Matt. 9:35). The key to Jesus demonstrating God’s power wasn’t just the power of the Holy Ghost, but also He knew the Scriptures and relied on the power of God (Matt. 22:29). Basically, Jesus showed up and God showed out by demonstrating the power His Gospel through preaching, teaching, healing.