The main purpose of evangelism is to reconcile men back to God. In other words, evangelism is spreading the good news that we can be reconciled to God through Jesus.
Evangelism began when Jesus came. As He walked in Jewish towns proclaiming that there is salvation for all who believe in Him, He started the evangelism movement.
One by one, people began following Jesus and spreading the gospel. First it was three fishermen, Peter, James and John who followed Him.
Then they invited others to also listen to Jesus. Over the period that Jesus preached, many who were healed by Him recommended Him to others.
We are told of the famous story of the Samaritan woman who went to call residents of her town after Jesus impressed her with His words. The message Jesus spoke to her brought a new light that she had never experienced.
After the death and resurrection of Jesus, He commissioned His disciples to carry on with the purpose of evangelism. By that time, the disciples of Jesus had already received salvation but Jesus wanted everyone to have a chance.
The gospel was then preached not only to the Jews but it also spread to the gentiles. Today, the whole world has an opportunity to be reconciled to God if people embrace the good news of Jesus.
Evangelism has helped keep the message of salvation alive through many generations and will continue serving its purpose of keeping the message of salvation alive until the return of Jesus.
That is the main purpose of salvation.