I pretty sure I'm going to end up laughing at Hindu deities during class
I would suggest you hold that in. Did your teacher say something that would make you laugh?
No, I'm doing it on my own free will
You shouldn't laugh at people just because they are different from you. Furthermore, other people's religious deities are sacred to them, so you shouldn't laugh at any religion.
Why does it matter, my perception is what's important.
That's a pretty inconsiderate statement. Other people's perceptions are equally important and you should be considerate of them. Let's try not being so self centered when we interact with others.