Christ saves us FROM our sins. Apostates offer to save people IN their sins. That is almost their most defining trait: They offer of spiritual rewards in the afterlife without continually repenting and improving, submitting our will to the Father's will in this life. Their promised rewards bring no spiritual endowments in this life, only later on, because they are false.
By contrast, Christ's offers to us are always based on repentance and are inseparably connected with the powers of heaven. He requires repentance, but gives us the Holy Ghost which we experience here and now. He requires temple worthiness, but gives us the temple which gives us revelation here and now and transforms our marriages here and now as we keep the covenants. Christ frees us from our sins by requiring us to repent of them. He can cleanse us of whatever we have repented of, and by so doing, can connect us to the powers of heaven here and now, which is the only real way to find ourselves connected with them when we come to judgement. It is the only way to save us.