OK, good. I thought you were denying the Trinity. My apologies. I fully agree with you that (a) “All you need to know is that you are a sinner and that a God exists that can save you...And all you have to do is ask Him...” and (b) “But knowing that will not save you...”
But you’re wrong on this point:
“And not knowing that will not prevent you from getting saved...”
Knowing that God is a Trinity in Unity will not save you. Satan knows that. (He may even understand it better than I do, which ain't hard.)
Not knowing it will not damn you, I think. You could not know it through invincible ignorance or other incapacity. You could have been given the grace to say the sinner's prayer and know as little about the Catholic Church and what she teaches as some of our antagonists here know (or even less), and not have their opportunities to learn. "A broken and contrite heart He will not despise." Willful ignorance on the other hand could prove to be mortal.
I think the "means of grace" provide immeasurable assistance, and sound doctrine is better and more useful than no or wrong doctrine.