Q. When someone has a guest on Shabbos day who did not make Kiddush Friday night (a not-yet-religous Jew), is it proper to say the full Kiddush on behalf of that person? If the person is not going to have in mind to fulfill their obligation (e.g., they are not religious and they do not understand that saying Kiddush is a commandment that G-d gave us), should one refrain from making the bracha for them? (Being motzi someone only works if they have in mind to fulfill their obligation).

A. Horav Shlomo Miller’s Shlit’a opinion is that indeed you can not be motzy or have someone comply with a mitzva by listening from another, if the listener does not understand the basic meaning of what is happening. Although he does not have to understand the translation of all the words being said aloud for his sake, he does have to comprehend the fundamentals and purpose of what is being recited.
Since the principles involved are not complicated, it may be correct to briefly explain them to him, then preferably have him read a transliteration of the Hebrew words, after he also reads their translation.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a