Evangelism doesn't happen automatically. But if you're not careful, it will disappear automatically from your church. Satan will see to that.
It takes constant effort and weekly reminders to develop and maintain a culture of evangelism in your church. It is a disobedient church that does not constantly win souls to Christ and disciple them into mature reproducing Christians.
In the Great Commission, Jesus told us to win the lost, baptize them and instruct them in the Christian life. If your church is not actively obeying His commission, it really has no reason to exist.
Then the word of God spread, and the number of the disciples multiplied greatly in Jerusalem, and a great many of the priests were obedient to the faith. (Acts 6:7)
And the Lord added to the church daily those who were being saved. (Acts 2:47)