Reading I Thessalonians 1

I'm reading Paul, Silvanus, and Timothy's letter to the church at Thessalonica. And I'm trying to break it down into little chunks so i can understand it. And I'm trying to put that into this blog, and I'm doing it with a needy cat in my lap. I wonder if Paul ever had to deal with a needy cat?

And the first thing that strikes me is that the grammar is sort of strange. If I was writing to Liberty Church, I'd write it "To the church  of God in Marietta." Not that Liberty is the only church in Marietta, nor is Liberty a part of the denomination called the Church of God.
But the letter says 'church OF the Thessalonians' 
'IN God the Father and the Lord Jesus Christ.'

I really don't want to put a whole lot of emphasis on prepositions, since it's been 30 years since I took Greek and I didn't study then, and I'm not pulling out my Greek New Testament, and I'm not even comparing the NASV with the NIV.
But let's just pretend that I did.
church of the thessalonians. Yeah, I can do that. It's the church composed of thessalonians. I don't have to stretch at all to understand it.
but: the church IN God the Father and the Lord Jesus Christ? Behold, I will hide nothing from you: I'm not even looking at the opening to the other letters to see how this compares with the other openings. I'm just gonna meditate on what it means. God is in the church; the church is in God. Are those equivalent statements?
AHA AHA AHA! Here comes the first sho 'nuff point that I want to make: I believe I have observed some confusion, or maybe just sloppy language, but maybe sloppy theology, about who it is we are worshiping. Now, maybe that comes from listening to prayers that weren't particularly well thought out. But this letter is pretty clear: Gods the Father, and the Lord Jesus Christ.
Some of the cults are pretty clear about who they aren't worshiping. We had a couple in the house a few weeks ago who were Jehovah's Witnesses, and they don't believe Jesus is God. And compared to that kind of defining clarity, I guess what I'm talking about has little significance.But:
The Father is God, and 
The Son is God, and
The Holy Spirit is God.
And the Father is not the Son is not the Holy Spirit.
I do NOT understand the Trinity.
I just believe that the Trinity is, and that there is a difference between the Father, the Son, and the Spirit.
I ain't up to being on Jeopardy or getting grilled to pieces about the particulars. It's just what the Creeds say, and it's really, really clear to me that the Bible says that Jesus is God, and that the Spirit is separate from both the Father and the Son.
I've got to stop now; my brain is full.