One Lord, One faith, One baptism.
You are going under the assumption that the gospel you were preached to is the same gospel that was preached to the early saints. I don’t know what faith you are, and frankly, it’s none of my business ( I don’t spend my time here on FR ripping other’s faith like some) but given the 30 thousand plus different “Christian” religions in the world, teaching different doctrines, they can’t all be teaching the same things that were given to the early saints.
One Lord, One faith, One baptism.
Certainly, those groups whose beliefs are truly Christian ... can all teach an agreed upon core of Christian belief.
Now, of course, they may do some other things differently (i.e. how they baptize, how often they gather, what music they use, etc.) ...
... just like the (15) plus churches mentioned in the New Testament (i.e. Rome, Ephesus, Philadelphia, Sardis, Smyrna, Colossa, Philippi, Galatia, etc.)