Juan is an exchange student from Cuba. He is shocked to learn that many students in America do not attend church on Sunday. Without thinking, he stated, "Everyone knows that Sunday is the Sabath and that is the right day to go to church". Juan is exhibiting:

False consensus

Explanation:

Juan believes that even though he is in different place and culture than the one he has lived in before, people would act the same way as he does.

Juan is exhibiting a case of false consensus where one overestimates how many people think or act the same way as they do and thus believe that their actions are normal.

Anything apart from what the person does is considered to be abnormal and out of the ordinary.

As we see in this case though, it is merely a matter of perspective.