Peter advised to be "ready to make a defense to everyone who asks you to give an account for the hope that is in you" (1Pe 3:15). I once had a pastor who used this scripture to show that you shouldn't just approach any stranger on the street to push the gospel. Instead he said the Holy Spirit would prepare the heart of a person to ask you a question. The hope in you "is Christ in you, the hope of glory" (Col 1:27). You have to make sure. "Test yourselves to see if you are in the faith" (2Co 13:5). "Conduct yourselves with wisdom toward outsiders . . . so that you will know how you should respond to each person" (Col 4:5-6). Therefore you should pray for God to "grant that Your bond-servants may speak Your word with all confidence" (Ac 4:29) and to "keep a good conscience" (1Pe 3:16). It is "'not by might nor by power, but by My Spirit'" (Zec 4:6). Paul wrote the Thessalonians that "our gospel did not come to you in word only, but also in power and in the Holy Spirit and with full conviction" (1Th 1:5). "My message and my preaching were not in persuasive words of wisdom, but in demonstration of the Spirit and of power" (1Co 2:4). The gospel is "the power of God for salvation" (Ro 1:16).
Jesus told them "'you will receive power when the Holy Spirit has come upon you; and you shall be My witnesses'" (Ac 1:8). John the Baptist said, "'He will baptize you with the Holy Spirit'" (Mk 1:8) and Jesus followed through when "He breathed on them and said to them, 'Receive the Holy Spirit'" (Jn 20:22). This would enable them to witness. However, they would also need the power that was promised. So they waited as instructed (Lk 24:49) and on Pentecost they were "filled with the Holy Spirit" (Ac 2:4) as he was "poured forth" (2:33). Jesus said the Holy Spirit would "'come upon you'" (1:8) and "the Holy Spirit came on them" (19:6). He "fell upon all those who were listening" (10:44) and "fell upon them just as He did upon us at the beginning" (11:15). They then were "full of the Holy Spirit and of faith" (6:5, 7:55, 11:24). "When they had prayed, the place where they had gathered was shaken, and they were all filled with the Holy Spirit, and began to speak the word of God with boldness" (Ac 4:31). Others "were unable to cope with the wisdom and the Spirit with which he was speaking" (6:10).