Theism rhymes with:
absenteeism, deism, absenteeism, amateurism, anthropomorphism, antidisestablishmentarianism, atavism, baptism, buddhism, careerism, cubism, culturalism, defeatism, deism, dimorphism, dwarfism, ethnocentrism, extremism, idealism, irredentism, isomorphism, jainism, jingoism, marxism, masochism, mccarthyism, modalism, monism, monotheism, multiculturalism, multilateralism, nazism, nestorianism, parliamentarianism, pietism, polymorphism, polytheism, pugilism, realism, sadism, sexism, surrealism, taoism, truism, vandalism, vegetarianism, vigilantism, voyeurism
Theism sounds like:
tacoma, tajima, takashima, takashimaya, takayama, taken, takeshima, takin', taoism, tashin, tashjian, tasm, tasman, tasmania, tasmanian, tassin, tassone, tatsuno, tauzin, teason, techno, tecogen, teichman, teichmann, teigen, tejan, tejano, tejon, tessman, texan, texscan, tezeno, theisen, theissen, thicken, thiesen, thiessen, thissen, thyssen, tieken, tieszen, tietjen, tigon, tijuana, tishman, tison, tognino, token, tokkin, tokuyama, toscanini, toscano, toughen, towson, toxin, tschumi, tsunami, tsuneo, tuchman, tuckman, tucson, tucuman, tudjman, tugman, tuscan, tuscany, twosome, tycoon, tyson