In to kill a mockingbird why did Mr Raymond pretend to drink?

He pretends to drink because

he says that the other town people could never understand that he lives with the negroes because that's the way he LIKES to live.

Some people don't like the way he lives and he doesnt care if they don't but he doesnt want to say hell with them.

It helps the people if they are given a reason acceptable to them. They think that Raymond is in the cluthches of his whiskey and that he cant help it and that's why he wont change his ways.

basically he deliberately perpetrates fraud against himself to cover his feelings for the Negroes.

hope this helps!! :) :P