Concern over my Bumper Stickers

Currently I have two bumper stickers on my car with atheistic messages. The majority of comments have been positive. I have had similar stickers on my car for going on 5 years now and I can count on one hand the negative comments I have received.

Last night I was greeted by this note when leaving the grocery store:

"If you don't believe in God, why are you trying so hard to prove He doesn't exist? The stickers show me you believe. You're just angry. I don't like a lot of things, but I don't go around trying to make others feel the same way. Peace, don't hate."

Here is my current crop of stickers:

Order your own

Order your own

This note is the most interesting one, to me, so far! The writer seems to be concerned. So concerned that I am wrong and troubled that they took the time to write me a note to tell me that they don't go around telling people that they are wrong or troubled.

Yea, let that sink in. In five sentences they managed to give advice and contradict it! On top of that they managed to make 4 wrong assumptions.

Lets dive in for the deconstruction!

"If you don't believe in God, why are you trying so hard to prove He doesn't exist?"
Well, Anonymous Helpful Person (AHP) you start out fine: I certainly don't believe in a God. But, none of my stickers are doing anything in the way of trying to disprove it's existence. They make the, quite logical, assumption that in the absence of extraordinary evidence something as fantastical as a God does not exist. The burden of proof is firmly on the other side here!

"The stickers show me you believe."
Ok, I really don't get where this assumption comes from! Given these two stickers where does one get that idea?

"You're just angry."
I guess this assumption comes from the same place the previous one does! I understand that both of these stickers can make believers angry, but it is certainly not from any overt anger expressed by me.

"I don't like a lot of things, but I don't go around trying to make others feel the same way.
My initial though is "why not"? If you dislike something, why not try to change it? Even more on point: "If you thought someone was mistaken about fundamental ways the world works, you wouldn't try to let them know?!"

If you saw someone about to drink drain cleaner you wouldn't tell them!? When I'm shopping and over hear another shopper get a wrong answer from a salesperson, I let them know.

I spent a while thinking up a list of examples. I wanted to come up with some good verbiage on how helping our fellow humans out is one of the most important duties we have. But then after a bit of reflection I realized that AHP was doing just what they told me not to do at the same time as they were claiming that they don't do it. That is an awesome bit of recursion there AHP!

"Peace, don't hate."
Again, I don't see any hate here. I certainly don't hate people just for believing in a God. Why would I hate someone for just getting an answer wrong? Why does AHP think I hate because I express what I feel is an important truth?