I agree with you that it is dishonest to misrepresent yourself.I have had people say that it's more productive to dub yourself an agnostic because it doesn't hurt the theist's feelings so much. It's nicer and gentler. But that seems cruel to me because I would be misleading them.
Furthermore, my priority on that matter would be to promote the use of the label "atheist" with skeptics reluctant to use it than it would be to choose language more to the liking of the Christian.
The very word "atheist" has been derogated by the Christians for eons. And as we see, drones like Dim work tirelessly to derogate atheism and science, often using religious words of all things, such as calling atheism a religion. So, my focus is to help reverse that, and put the offending theist on the defensive instead. Here's a nice quote regarding that matter:
I always flinch in embarrassment for the believer who trots out,Atheism is just another kind of faith, because its a tacit admission that taking claims on faith is a silly thing to do. When youve succumbed to arguing that the opposition is just as misguided as you are, its time to take a step back and rethink your attitudes.- Amanda Marcotte