Words can trip us up.
Where we stand in time and which direction we look can fool us.
For instance, was Judaism a formal religion that you joined or were kicked out of?
How would Jesus have responded to the question: "What religion are you?"
Did such a question have any meaning at all for people in the 1st century?
Ideas and stories spread by people telling about them and other people listen. But, how a person hears/understands is a separate feature of transmission.
Everybody who calls themselves "christian"--if you examine their thinking--believes in a DIFFERENT idea.
That is because people, although human, are not clones.
When it comes to BELIEF you can substitute "opinion". Dragging "god" into it only amplfies the hubris.
The idea of a "church" is something today it was never thought of two thousand and umpity ump years ago.
There were people who believed in certain ideas and tried to conform to the morality of them. While, at the same moment, somebody sitting
in the same room with them had different ideas and might mightily disagree with the first guy.
When Jesus was with his disciples there was a lot of confusion, misunderstood communication and awkward bickering.
Jesus spoke a parable about wheat and weeds in which he indicated you couldn't tell them apart and should NOT TRY to separate them out!
You might just get rid of wheat while trying to excise the weeds!
But, men are faulty even with the best of intentions.
The Catholic Church became (that indicates a slow process) something and continues to become something and can only be said TO BE something
from moment to moment. Which is to say it didn't ORIGINATE so much as it coalesced.
In our vocabulary and grammer a word REPRESENTS meaning without itself BEING a meaning.
As a majority of writers and speakers change what that word intends to express.....the dictionary eventually changes to INCLUDE the new use. When the old use dies out the new use BECOMES the meaning, but--importantly--it is still the SAME WORD.
BOTTOM LINE?
Human thought, ideas, beliefs and bodies of knowledge tend to bend, warp, melt, coalesce and redefine over time.
There is opinion and it is either very soft on one end or very solid on the other end......but--it has to stand the test of its own claims to be anything at all.