Salvation rests on trusting the real Christ, not on a label. Official Latter-day Saint teaching describes a materially different God and Jesus than historic Christianity, which is why the object of faith matters so much here.
The Grace Answer
Start where every honest answer to this has to start: faith is only ever as good as the One it rests on. Salvation is not a label you wear. It is trust in the real Christ, the eternal Son who is fully God. That is why this question is heavier than an ordinary denominational disagreement.
Official Latter-day Saint theology does not simply read the same Bible a little differently. It redefines the foundational things: the nature of God, the identity of Jesus, human origins and destiny, and the way salvation works. When the God being trusted and the Jesus being followed are described as fundamentally different beings than the eternal Father and Son of Scripture, the concern is not tribal. It is whether saving faith has the true Christ as its object at all, and faith rests on who Jesus actually is.
Hold the system and the person apart
Two things must be held at once. We can say plainly that the official system teaches a different God and a different Jesus, and still refuse to pretend we can read any individual heart. Plenty of people within that world are sincere, searching, and genuinely drawn to Jesus, and some may be trusting the real Christ more truly than the system around them teaches. God knows exactly who is His, and He judges justly.
So what do we actually say to a person? Not a verdict on their soul, which is God’s alone, and not a slogan. We say what we would say to anyone: you are saved by grace through faith, and that not of yourselves. It is the gift of God, not of works. And the Jesus who saves is the eternal Word, God in the flesh, with no one coming to the Father except through Him.
Point them, gently and without contempt, to the real Christ. He is the whole hope, and He is more than enough. This is not about winning an argument or feeling superior. It is about the plain truth that saving faith needs the true Christ to rest on, and about loving people enough to introduce them to Him. Speak it with humility, and leave the verdict where it belongs, with the God who judges justly.