One of the ten commandments is “Thou shalt not bear false witness.”
The ethics of belief is that “it is wrong everywhere, always, and for anyone to believe anything without sufficient evidence.”
If you are to seriously try to obey the commandment not to bear false witness, you must try to adhere to the ethics of belief. If you believe without sufficient evidence, then you run the risk of believing falsehoods, which means that you run the risk of bearing false witness.
The reason the ethics of belief is true is that, otherwise, we risk believing falsely and thereby run the risk of doing wrong things — doing them unintentionally but doing them nonetheless.
For instance, if you believe that ceremonies instead of ambulances benefit people in car crashes, you endanger the injured instead of helping them, which is wrong.
If God is good, then He wants you to believe only in accordance with the evidence. You have to do this in order to love your neighbor as yourself.
It is not anti-religious to criticize people for believing stupid things. It may be anti-bad-religion, but so what?