A Jehovah's Witness once said that the Christian God of the Trinity has Multiple Personality Disorder (MPD). This goes to show their complete lack of understanding of the Trinity and how to explain it.
God does not have Multiple Personality Disorder (MPD). He created us in His image, having three parts. You have mind, body and spirit. The Bible says we have "spirit, soul and body" (1 Thess 5:23) So, the soul is the mind, will and emtions. So you have a physical body for the physical world, a spiritual body for the spiritual world, and a mind/soul that connects the two. So you are three parts in one person. God is the same, but His three parts are far more powerful than ours. Yahweh's (God's) mind is The Father. His physical body is the Son, Jesus, and His spirit body is the Holy Spirit. Three in one. This unlocks the mysteries of verses in the Bible like the one in John where he says, "No one has seen the Father at any time." Why is that a problem? Because Moses saw God on Mt. Sinai. And Abraham saw God in Genesis 18. And many of the prophets say they also saw God. If they did not see the Father, who did they see? It's simple: Can you see your mind? No. Then you cannot see the Father either. They saw Jesus if they saw God in the physical world. And they saw the Holy Spirit if they saw God in the spiritual world (heaven). Jesus said, "If you have seen Me, you have seen the Father." I found out recently that this is exactly what the Baptists' teach, and I felt deprived that I had to figure it out on my own when I could've just asked the Baptists. lol