If morality is subjective...

[robvalue]

Accepting an objective moral standard makes you entirely amoral. You are without morals. You blindly do what you are told, ignoring your own observations about the help or hindrance of your actions upon others.

And no theists do this anyway. They cherry pick, the honest ones will admit this. But even if they didn't, the usual books are so filled with contradictions that you can't follow it all consistently, it's impossible. So you end up making choices about how to resolve these problems, hence you're making your own moral judgement.

Proper morality is pretty easy to grasp for anyone who understands what helps someone and what hurts them. There are very few people who could honestly claim they have no idea. To throw all your empathy, reasoning and even gut instincts away to adhere to an arbitrary "rule" that everything about you tells you is wrong, is... wrong. The only reason to behave this way is out of fear. Like someone has a gun to your head, or your loved ones. Of course, this is exactly the case with religion. God holds your soul hostage while you dance to his arbitrary tune. Or rather, what people tell you is his tune. And they can't even remotely agree what that tune is.

Only a sociopath could truly say that they think all subjective "morality" is equally valid. It's a desperate theist rationalization. Secular society has laws, but it doesn't dictate morality down to the letter like religion, so that is another false equivocation that's often made. Also, theists would want the law to be upheld, even against people acting in accordance to the holy book they worship.