The doctrine of the Trinity is hard to teach, because there are so many ancient heresies to guard against and because, well … it’s complicated. But, the Scriptures present God as triune. That means we need to teach about Him. We need to teach Christians to know Him and love Him as He is; and He’s triune.
I’ve spent a lot of time reading about the doctrine of the Trinity; probably more than most pastors. That, and Christology, are my own hobby horses. Some people find joy in making complicated end-times charts. Others find fulfillment in being a Baptist fundamentalist. Still other Christians find their religious self-identity in a particular view of the doctrine of salvation. I like to study about who God is, and how He’s revealed Himself.