The God they believe in is exactly the same as what we call the father. I do not even know if the Trinity is true nor why it matters but the father and Yahweh are identical entities in personhood regardless.
"I do not even know if the Trinity is true nor why it matters"? Hmmm? I don't know, but it might make a slight difference in what a person believes?
Hmmm? Jesus is God? Or, no he's just a man... a real, real good man. In fact, a perfect, sinless man. But that's impossible, because all men are sinners? Therefore, Jesus is not just a man, he must also be divine? Hmmm? He must be half God and half man? No, he must be all God and only seemed to be a man? No, he must be both all God and all man, and yet, without sin. Now where's my Bible so I can find verses that make it seem like that is what the Bible was saying all along. Oh, perfect, Adam sinned and all men inherited sin from him. Oh cool, here in Isaiah I can take this "virgin" or "young woman" story, it shouldn't make too much difference if it was a virgin or young women, both words can sort of mean the same thing... and then, I'll make this story a prophesy about a child born without a father. That way, he doesn't have the inherited sin from Adam. Hmmm, now what? Okay, God got her pregnant. So God is the kids real father, so the kid is... God's son. So the kid is like God? Or, he is God!
So how is the son and the father the same being? Oh, I know, the one God is really two in one, God the father and God the Son. Hmmm? What about Mary, the woman? Mary, mother of God? Some people might buy that, but Mary never married God. That would make God an adulterer. We can't have that. What to do, what to do? I know, she was just a surrogate. She carried God's son, but she's not the real mother. She only donated the egg. So, perfect, God the father and God the son, The Holy Bi-God. Oh no, bi? That doesn't sound right? Hmmm? What to do, what to do? I know. I'll add God the Holy Spirit. Three Gods in one, the Holy Trinity! It's virtually the same God, just different. It shouldn't really matter. Maybe later, we'll add a storm god and a fertility god. And then, who knows, maybe we'll make an evil twin god to fight against the good god.
Yeah, we can have an epic battle in heaven. And all the Earth people can join in and take sides. And the evil god can mate with human woman and make half god and half man super things, that could fly and turn invisible and do all sorts of cool evil things. Then the good god could get a kid with a sling-shot to kill this giant monster evil thing that was terrorizing the Earth. Then the bad god sends an army of flying monkeys to get him, but he escapes by using a magic ring. Hey wait, I'm getting carried away. At some point people are going to quit believing this is true and realize it was just a myth... a really elaborate story that I just made up. Yeah, I better stop now before it gets too unbelievable.
So the absolute truth is: There is one God. He has a spirit, well actually he is a spirit, but he has a special spirit, The Holy Spirit, that got Mary pregnant. She had a son that was God's son, but was also God and was with God from the beginning, even though he hadn't been born yet. But, he was there in spirit. So, in the beginning there was God, an almighty spirit, and the spirit of his yet to be born son and the Holy Spirit, all three spirits, which were all one, one spirit, yet separate. They made a bunch of spirit beings they called angels or for short, messengers. These spirit beings had nothing to do, so one of them got bored and rebelled. One of the Gods, the Father, got mad and cast this bad angel out of heaven into... nothing? No, I remember now, God created the heavens and the Earth, that way he'd have a place to cast the evil angel out to. One third of the billions of angels weren't that smart, they decided to follow the evil angel.
In the mean time, God had created Adam but forgot to create Eve. God's son, the other God, had to remind God of the original plan, the plan of salvation that they had devised before the Earth was even made. This plan needed Eve, because she was going to screw up and listen to a talking serpent and eat a forbidden fruit. Wait, wait, wait, I'm sorry, nobody's going to buy this. It's like its fantasy or Sci-fy or something. Who would ever be gullible enough to listen to a Sci-fy writer? That would be stupid.
So back to the point: is the trinity true? Who knows? And really, why would it even matter. One God, three Gods, one in three, it's all almost the same. Except, if we're going to add Gods, can we make it official and add Krishna? I like him, and it would give Jesus someone to hang out with in heaven.