I feel like this is saying you're a Christian because religion is useful regardless of whether it's true. That's cool man, I'm not here to yuck your yum.
Sure, but all analogies are flawed. Yours is not as offensive to me as you might have hoped because I’m agnostic. But I can also flip it on its head:
The problem with religion comes when it’s used as a justification for horrible acts—just like one might use the lack of free will to justify horrible acts.
Sorry, I genuinely wasn't trying to offend you, though I can see why it came off that way. I just meant to convey I'm not on some mission to convince people of anything. If it's helpful or makes people feel good to believe in free will, that's good enough for me. Even if I were 100% sure of there was no robust free will, I wouldn't be interested in changing people's minds.