Reddit reviews Evangelism and the Sovereignty of God

In addition to what /u/tphelan88 said, I would say that evangelism is not primarily about conversion, but about worship. We evangelize not primarily to save people, but primarily to increase true worship of God. Conversion is necessary for someone to truly worship, and so it is a fruit we desire to see from evangelism, but if everyone truly worshipped God, there would be no evangelism. After Christ returns, there will be worship, but no evangelism.

Because we are seeking to increase worship of God, the act of evangelism itself is a form of worship. Thus our evangelism has a fruit, whether or not it leads to conversion. When we preach the gospel to everyone, we know that our work is always bearing fruit, even when it doesnt always bring conversion.

If you are interested in a reformed/calvinistic perspective on evangelism, check out Let the Nations be Glad! by John Piper.

Edit: Also, check out the classic Evangelism and the Sovereignty of God by J.I. Packer

Evangelism and the Sovereignty of God by Packer is the seminal work, and it's a quick read. Kind of like a Bondage of the Will-size treatment of a reformed doctrine of evangelism. Amazon link.

An approach to evangelism that is not only extremely helpful for all but also places the right emphasis on the power of God in conversion is Questioning Evangelism by Randy Newman. Amazon link.

There is a good, very short, book by J.I. Packer called Evangelism and the Sovereignty of God.

https://www.amazon.com/Evangelism-Sovereignty-God-J-Packer/dp/083083799X

It's a great read for understanding how those who believe in sovereignty and predestination still work hard at evangelism.