"Baptism" does not imply "water", it MEANS "immersion". That could refer to many things, including water. It appears that by your reading of Matthew, that it is man who actually brings down the Holy Spirit on behalf of his fellow man. God does not indwell as He chooses, NO, men make the decision and God is summoned into the baby.
I thought you were a believer in the perspicuity of the scripture.
On the basics, I am, but that doesn't mean that further study isn't needed on finer points. The Bible is a treasure trove that can more than satisfy any appetite.
[On John 3] But in 5, according to you, Christ abandons the "womb" terminology already offered by Nicodemus in favor of the very unclear "birth of the water", especially unclear in the context of both baptism of John and the scriptural context. In 6, however, Christ already speaks of "flesh". Why did He not stick to the "water" terminology in 6?
He didn't abandon the terminology, He confirmed the idea by using a like term, so there would be no confusion. Wasn't it you who said that the Baptisms of John the Baptist didn't have the same effect as they do today? Well, that's all they had at the time, so your argument doesn't "wash". :)
So why would Christ state the necessity of physical birth so forcefully, if that is what He is referring to in 5? Nicodemus asked Him about the second birth, not the first.
He was doing what He always did, explaining something using a point of reference that the hearer could understand. He was saying that all the "newness" you associate with regular birth is similar to the "newness" that goes with rebirth (a new creation).
I am not sure what is your argument here. Is baptist baptism not by water?
The Bible is a treasure trove that can more than satisfy any appetite
Except, it seems, when you come across a verse you don't like, like Acts 8:30, and then is just becomes a "guy explaining a scripture to another guy".
He didn't abandon the terminology, He confirmed the idea by using a like term, so there would be no confusion
Accoridng to you, Jesus introduced tremendous confusion. Nicodemus calls natural birth birth of the womb. Christ refers (you think) to the natural birth as birth of water. But in the next verse He is back calling it birth of the flesh. That, when water is how John performed his baptism of rebirth.
Wasn't it you who said that the Baptisms of John the Baptist didn't have the same effect as they do today?
That is correct, but the two are related and the johannine baptism had established the connection between baptism as a ritual, second birth, and water, by the time the conversation with Nicodemus is taking place.