WordNet records no synonym and no antonym for shema. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a liturgical prayer (considered to be the essence of Jewish religion) that is recited at least twice daily by adult Jewish males to declare their faith
“as soon as Leonard learned to talk he was taught to recite the first words of the Shema, the creed of Judaism which originated on Sinai with Moses and is recited daily”
Synonyms, antonyms and the broader and narrower relations for shema come from Princeton University’s WordNet. Full sources and licences.