faithless
adjective uk/ˈfeɪθ.ləs/ us/ˈfeɪθ.ləs/
(NOT LOYAL) 不忠诚的;不可信赖的not loyal and not able to be trusted
(配偶或性伴侣)不忠贞的not faithful sexually to your marriage partner or usual sexual partner
a faithless husband 不忠的丈夫
(NOT RELIGIOUS) 无宗教信仰的with no religious faith
Related words: faithlesslyfaithlessness