or: Finding the Trinity in the Old Testament
This is the sermon I delivered at ValleyView Baptist last month when I filled in for our pastor who was traveling. Yes, it is audio only, but if anything, that should be an incentive to click on it (though my voice is nothing to write home about either).
You may find the info useful if you are given the opportunity to witness to people of the Jewish faith, Jehovah Witnesses, Mormons, Muslims, or others who reject the Trinity as an invention of Christianity.