In the list of spiritual gifts in Rom. 12 and 1 Cor. 12, I am struck by the fact there is no "gift of evangelism." Evangelism was something that every Christian did eagerly and willingly. In Acts 8:4, all Christians were evangelists. Everyone else went about preaching the word. The church practically exploded overnight with many wonderful people stepping forward declaring their commitment to Christ and submitting to baptism to walk a new life.
While I have not witnessed conversions in the 1000's, I have seen over 60 people baptized in less than a week. I have seen a little church of 40 people nearly double in size in a week. It was invigorating. It was exciting! It was pure joy!
It can be done only by the power of God. The power of God for salvation to everyone who believes is the Gospel (Rom 1:16). The Gospel is the death of Jesus for our sins, his burial and resurrection (1 Cor 15:1-4). Paul focused on the power of the Gospel in his ministry and God worked powerfully. I still see the same thing happen time after time today through ordinary people!