Can one be resistance and claim Francis is not the pope?

For the Catholic Church to lose Her Unity of Government, even temporarily, would be to lose an element of the Mark of Unity, at least temporarily. Id. If there were times when the Church did not have this element of the Mark of Unity, then this element would never be part of the Mark, because the Marks of the Church are inseparable from the Church and are signs by which we can always discern the true Church. 1917 Catholic Encyclopedia, article: Unity (as a Mark of the Church); Catechism of St. Pius X, section: Ninth Article of the Creed, Q.13.