Straggler;
Just to make sure we are on the same page I am talking about preaching the Word, not "witnessing" door to door, or on the street corner or protests and rallies. I am talking about preaching the Word of God as it is instructed on Lord's Day to a congregation.
But to what end?
Preaching seems paradoxically pointless in light of what you have said about predetermined salvation.
You are not just preaching to the converted. You are preaching to those who could never be anything but converted regardless of your preachings.