How does the contrast between the Meursault and the mourners suggest how social conventions may, in fact, make us strangers" to our true feelings?

Meursault is aloof for much of the novel. When it comes to matters of love, death, sex...there is a sense of otherness to Meursault. He, like the author, does not believe in God and comes to the realization that one must struggle against and with the Absurd in order to create meaning in a meaningless world. He leads a highly indifferent life through much of the book which includes the funeral of his mother. You can check out more below,

http://www.gradesaver.com/the-stranger/study-guide/character-list/