I think Ms Lopez is overly concerned to the threat to Christianity in Europe by non-believers.
Most Europeans are indifferent to the religious beliefs of others if they keep them to themselves. The treat to Christianity in Europe is because people are increasingly rejecting organized religion. (See Pew Research for some numbers on the decline of affiliation in Europe and America). Official church membership is not a good indicator of beliefs however, since many maintain membership only in order to have church weddings or funerals - i.e. for cultural tradition reasons. Maintaining cultural tradition is often the reason that they oppose the building of prominent mosques in their cities