Calvinist Evangelism...

I'm sure this topic has been addressed here many times before, however, I am knew to the board, and really don't have the time to go searching for it.

Basically, I want to know from Calvinists, what is the purpose of evangelism, other than the simple fact of obeying the Great Commission. If all our choices are already pre-determined by God, then what use would their be in spreading the Gospel? Do Calvinistic churches actively pursue soul-winning and/or witnessing?

Thanks for the help!...

Calvinist Evangelism...