I will grant your reply about the Liberal Mainline Protestants but the question of the need for Baptism or the dispute between Arminianism and Calvinism is hardly of little import.
However, most other denominations who do have disagreements, do not disagree on anything that is critical to salvation.
The fact that there are different denominations does NOT by default mean or even need to imply, major differences in doctrine or beliefs, and that they think they are right and everyone else is wrong and not saved.
Many of the differences can be stuff like church governing board preferences, or differences in focus on mission.
To try to portray the fact that there are numerous denominations as evidence that there are either that many differences of interpretation of Scripture is disingenuous. That's simply not the case.
Here are links to several denomination's statements of faith.
I would defy anyone to find anything significant in there statements of faith that would be considered important enough to affect one's salvation.
Paul even allowed for areas of debate; disputable matters as he referred to them as in Romans 14.
Lockstep adherence to ONE denominational creed is not required or demanded by God.
And even if one did verbally, intellectually agree with that, is does not ensure the salvation of that person.