Trinity: it's not so much if you believe it or not. If you question it, they know you're not a good little beast in their corral. That is why the church superimposed the Trinity as a litmus test. It shows whether you accept the church's human leadership as replacing your own conscience. Is the Trinity self-evident? If you think about it, isn't it hard to see what in the heck they mean?
Does the Holy Spirit speak through your own conscience in free inquiry, or through a church-controlled state's "office of official dogma?"
Speaking of Jack Nicholson -- what an actor.