How did Saint Meargert become a saint?
There are a number of saints named Margaret but none named Meargert.
Saint Alexius of Rome died as a martyr in the early 5th century and was declared a saint soon afterwards by the Catholic community. He was not canonized as the official process of canonization was not fully instituted until the 12th century. Today, only the pope can declare a saint after a lengthy investigation by the Sacred Congregation for the causes of saints.