Truth leads to Salvation. So, of course all Truth is important to Salvation. You can't just lie your head off about practically everything in the material world and expect God to save you. If we are in a War of Good against Evil and we must pick a side in that war and if Good = Truth and Evil = Lies, then we should be loyal to The Truth and unfaithful to lies. There is objective truth, it is knowable, as surely as God is knowable. If we can't think straight about the natural world around us, then how are we going to think straight about the supernatural! If we can't be honest about the natural world, then how can we be honest about the supernatural world. Both worlds have the same Maker. Why should we care about the Old Mass, vs The New Mass, if Truth doesn't matter and knowing the truth, experiencing the truth and living it in the little details of our lives and worship doesn't matter. Of course it matters! Shall we say, the new mass is good enough for salvation, so lets forget about this latin mass? No, because we recognize the truth in the latin mass and the dangerous lack of clarity and reverence in the new mass.