I’m old enough to remember pre Vatican 2 and yes, it was taught that only Catholics were saved.
I remember in the late 60’s even, I joined a Girl Scout troop that met in the basement of a ***GASP*** BAPTIST church.
Well, I wasn’t sure if going into that church was a sin or not, and neither were my parents. They checked and found out that as long as I went in the back entrance and right into the basement where they met, I was OK. But under NO circumstances was I to go into the sanctuary. THAT would be a sin if I went into the section where they actually worshiped.
I thought it was more like only Catholics had the potential to be saved, but they had to wait until they died to find out if they led a good enough life to earn Heaven.