Well, Separate in the sense that they are no longer together! I find it preposterous that you think everyone else that doesn't think like you do is a heretical thinker or teacher. Considering, the bible is not 100 percent clear on the mystery itself.
"Jesus is the word, the God, the flesh, the Spirit, the man, the Father, the Son, the Alpha&Omega, the Lord God Almighty, He is all!"
God is God, regardless of how we comprehend or not comprehend. He can do what He wishes, included be three different persons if He wishes. Again I will say I believe in the Trinity, as three distinct and separate persons. My understanding might be different than yours, but that is the doctrine of the Trinity. There are not three separate Gods, but one GOD. However He decides to manifest or accomplish three persons, that's Him; as stated, nobody knows the awesomeness of God and how He works.
I hate to say this, but whether you know it or not, you are contradicting yourself, while stating that you agree with the statement of the man teaching Modalism.
You say you don't believe the same as the above quote, while stating the same thing.
God is not into roll playing.
I think, roll playing is what you believe in, because that is the only picture you have that makes any sense to you.
Perhaps if you were to look at God more along the lines of a body, it might give you a better picture of how God can be three, yet one.
The bible talks about the body being of many parts and members, yet it is one body, controlled by the head. For the most part, that is true.
The hand, foot, ear, or tongue are not the same as the head, but distinct. But because they are of the same body, what you do to one part affects the whole. Every part is of one body, and yet, though each part functions in an area the others cannot, if you were to inflict one member, the whole body would feel it and react as one, guided by the head.
God is similar to the above example, only it is more on the spiritual side.
Both God and man are alike, in that, we both have a physical flesh and bone body, for Jesus is God and He took His flesh and bone body with Him to heaven.
We both have a conscious sole. That being the Father.
We both have a heart of flesh, the Spirit of God dwells in, and flows out of. That being the Son.
And we both have a spirit
man, That being the Holy Spirit. Not a thing, but a person or being that thinks and has feeling of His own.
Even though the Father is the head, both the Spirit and Son/Heart, can and does affect the decisions and attitudes of the Father, even as our spirit man and heart affect our decisions and attitudes.
Have you ever wondered out loud as to why you would say or do something that you regretted later? Such as saying something bad to one of your children who kept doing the same dumb thing repeatedly, only to apologize later. If you said it without thought, then that was most likely your spirit man that caused you to get angry, and your heart, that used your mouth, without thought or before the conscious part of you could take control, before blasting your child.
God the Father is like that too.
If you get the Holy One of Israel/Jesus upset, because He is part of the makeup of God, He will cause the Father to be upset and react.
I have a little saying that the bible backs up as being true. Whosoever or whatsoever controls the heart, controls and/or affects the man.
The same hold true with God.