"Apple could not verify PocketBible is free of malware that may harm your Mac or compromise your privacy."

If you get this message while installing PocketBible, it does not mean what it says. Apple is not refusing to install the app because it might be harmful, but rather they are refusing to install the app because you've told it not to allow apps from outside the App Store. 

To install PocketBible, you simply need to go to Settings in the Apple menu, choose Privacy & Security, and scroll down to the Security section. Look for:

Allow applications from

and change it to 

App Store & Known Developers

After you do this, you should be able to install the app.

Laridian is a "known developer". We are enrolled in Apple's Developer Program, and have been for years. 

Our apps are digitally signed. A valid signature says "This app was created by Laridian, Inc. and has not been altered since it was signed." 

Our apps are also notarized by Apple. This means, "Apple has scanned the app for known malware and has confirmed Laridian's identity." So when they say they can't verify that PocketBible is free of malware, that's just false. They just refuse to look at it — again, because you have an option set that tells them not to.