Sentence:  It follows , then , provided the possibilities have been exhausted , that the only real alternative is the general viewpoint of the `` left '' , which has been represented on the Continent by Fritz Buri and , to some extent <WSD>at</WSD> least , is found in much that is significant in American and English theology . 
Meaning of the word marked with <WSD> tags:  if nothing else (`leastwise' is informal and `leastways' is colloquial)