在「中國禮儀之爭」中，嚴謨以其豐富而專業的經學知識，為耶穌會士提供了很多中國傳統禮儀方面的材料和信息，從而使耶穌會士在與多明我會、方濟各會等修會的論辯中擁有更多的優勢。嚴謨採用了經學的詮釋體式和詮釋方法對中國祭禮的性質加以辨析；其在從事祭禮性質之辨析時，對典籍所載內容的徵引是有選擇性的；其還將中國祭禮與天主教的相關禮儀進行比較，以明中國祭禮之性質。嚴謨對於中國祭禮所持的基本觀點如下：其一，中國祭祖是後人對先祖追思和感念的方式，是世俗的教化行為，而非宗教儀式，其中沒有求福之義；其二，祭孔是遠古時期祭先聖先師傳統之延續；祭孔僅是表達對孔子的敬仰，相關的儀式並不神秘，也沒有祈福之義；對於那些有佛教和道教元素的中國祭禮以及部分民間信仰，皆應禁絕。

Yan Mo used the hermeneutic style and method of Confucian classics to analyze the nature of Chinese sacrifice; its citation of the contents contained in ancient books is selective; it also compares Chinese sacrificial rites with the relevant rites of Catholicism. Yan Mo believes that Chinese ancestor worship is a way for future generations to remember and feel for their ancestors. It is a secular educational behavior, not a religious ceremony, in which there is no meaning of “seeking happiness”; offering sacrifices to Confucius is not mysterious, nor does it have the meaning of praying for blessings; Chinese sacrifices with Buddhist and Taoist elements and some folk beliefs should be banned.