Both classes are defined by whether the two relevant terms can coexist, not by whether a sentence is complimentary or critical.
ClassCriterionCore example
ConcordantThe terms may coexistA living person also receiving the life of guidance
OpposingThe terms cannot coexistCalling an existing but useless person nonexistent
One must not equate different respects of existence. The coexistence of physical and spiritual life is one claim; being literally both existent and nonexistent in precisely the same respect is another.