I grew up in a church that had “the truth”. If you did not follow the plan of salvation as taught in the Bible as they understood it you were not going to heaven. This argument works great on those who accept this position. Arguments are not one size fits all. The point of pointing out the many denominations is this: if the God of the Bible is the one true God, he did a terrible job at explaining exactly what he wanted us to do. It is also confusing why a god would need to use fallible humans to communicate to us what he wants. If God is powerful enough to build Universes, he should be able to communicate in a way that is not subjective to personal opinions.
First off, the first question I would have to ask, can God communicate on an individual basis? There are many people, including myself, who knows what God wants us to do, because God spoke to us individually. An example of what I mean, a person on a loudspeaker we can say is effectively
communicating to a broader range of people than someone having to rely strictly on their voice alone. The person on the microphone's voice is enhanced enough to where people can hear them from 2 or 3 blocks away. But, he has no control as far as choosing, or limiting who he communicates with. Some people seem to think that God cannot communicate individually, or for some reason wouldn't.
As far as your church, yes, some churches and denominations have a strict view on salvation. Some think that someone cannot be saved if they don't
speak in tongues for instance. Or, they must be baptized in addition to acknowledging Christ as savior. But the majority of Christians, particularly in
America, understand that differences in doctrine does not separate believers. John 3:16 among some other verses are catalysts for salvation for many believers because this often seems to be where the supernatural awakening takes place. (Or, the Born Again experience). And we don't really
know the dynamics of how this happens. When someone receives Christ, and they have the experience to go with it (which by the way varies tremendously), doctrine or definition of salvation is pretty meaningless since they just encountered the savior. And since it's tough to understand as
far as it's dynamics, there's more of a universal acknowledgement of salvation in the traditional sense, than, say, the tribulation timeline, eternal security, age of the earth, etc.