Assumption of Mary (Salvific issue) Catholic

# Problem description # A protestant made the following two arguments about the assumption of Mary: 1. A catholic that doesn't accept the assumption of Mary will be excommunicated from the Catholic church 2. A catholic must believe in the assumption of Mary ---------- # Questions # - Are these arguments correct? - Is the assumption of Mary a salvific issue for Catholics? - If it's not a salvific issue why is it "good" to believe in it as a Catholic? The last question was asked from a Catholic perspective.