My "problem" with the doctrine of the Trinity, is that there IS NO clear definition of the term. How can one espouse a doctrine, which is not clearly defined?
SDA pioneers and Catholic theologians each individually understood the term differently. It's like wrestling with smoke. You can't get a good grasp of anything. The immediate excuse is that it's just too far beyond our ability to understand.
How can we believe in something that is beyond our ability to understand - even at the most basic level? No wonder the agnostics think they have a good excuse.
Why even spend time discussing whether "God" is a Trinity - if you cannot define "Trinity" ?
You would think, if "God" really IS "a Trinity", that He would have left some strong statements to that effect.