There is not much holiness in having an evil woman as Pope. How could she be the Vicar of Christ?

The Catholic Answers

Some misguided writers have spoken of a female Pope named Joan, who was supposed to have reigned from 855 to 857 A.D. But never was a greater hoax put over a credulous public. Voltaire laughed at the gullibility of fools who believed this tale. The Encyclopaedia Brittanica says that she is a pure myth. Chambers Encyclopaedia calls her “a fabulous personage.” Gibbons, in his Decline and Fall exploded the legend half a century ago, saying, “A most palpable forgery is the passage about Pope Joan, which has been foisted into some manuscripts.” Her advocates bear testimony against themselves, producing echoes of the 14th, 15th, and 16th centuries—at least five centuries after her supposed death. She has been annihilated by two learned Protestants, Blondel and Bayle, but others still attempt to save this poor engine of controversy.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty