That doesn't follow at all.
Nope.
Islam is driving both the terrorist and the accountant to do exactly the same thing: treat "God wants you to." as a good reason to believe something and a good reason to do something. How do you figure that isn't inherently evil? "It is wrong, always, everywhere, for anyone to believe anything on insufficient evidence."
Your argument is wrong because it is based on a number of flaws. 1st, it assumes Islam is driving their actions rather than simply one of many factors.
In the first place, "one of many factors" is a new argument for your contention, not the argument you previously made. Even if it's a
good new argument, that doesn't change the fact that your contention doesn't follow from your previous argument, which is what I said.
And in the second place, "their actions" is ambiguous. Which of their actions are you talking about? If you mean Islam is only one of many factors affecting the two Muslims' respective practices of terrorism and public accountancy, yes, that's true, but so what? My argument didn't assume Islam is driving
those actions. My argument only assumes Islam is driving the particular action I specified: treating "God wants you to." as a good reason. If you're proposing that Islam is not driving
that action, but is simply one of may factors, share. Name another factor. What the heck do you think there is besides religion that would incline a person to treat "God wants you to." as a good reason? It's not as though God Himself is actually appearing and impressing theists with His virtue, His charismatic personality, or His power and vengefulness.
2nd, it conflates "wrong" with "evil". For example. your argument is wrong but it is not evil.
I'm not conflating those at all. Let me be very clear here: I'm not condemning Islam for teaching a falsehood; I'm condemning it for teaching immorality. It isn't just that "God wants you to" isn't in point of fact a good reason. It's that treating "God wants you to" as a good reason is morally equivalent to handing your car keys to a drunk. Your body is a tool, just like a car, only more dangerous; and it's your conscience's job to make sure that tool is used safely; and when you let something else trump your conscience, your conscience is abdicating its responsibility.
3rd, belief (as opposed to knowledge) requires some element of faith which means there is insufficient evidence. People act all the time based on belief. Most human interaction between strangers of all types is based on the belief of trust. There is nothing inherently wrong acting on belief when there is insufficient evidence.
In case you didn't recognize it, I was referencing
W. K. Clifford's famous 19th-century essay. If you have a major disagreement with Clifford, what's wrong with his argument? If you're just proposing to carve out a minor exception for beliefs about insignificant or abstract matters, suit yourself, but it probably doesn't change anything with respect to the terrorist and the accountant.
Normal trust of strangers is based on evidence -- we have ample experience with strangers behaving well, and we know there's a good psychological explanation for them behaving well, since we live under governments that enforce good behavior. Under hunter-gatherer conditions there's a lot less trust of strangers, for good reason.