How to get Anathema working on Mac with Gatekeeper (10.7.5 and up)

Gatekeeper is a new security feature turned on by default in later versions of Lion (10.7.5+), and on Mountain Lion (10.8.0+). It requires that all software be signed by its developers, and all developers be approved by Apple (and pay them $99/year for the privlidge). Because this is a free piece of software, we're unwilling to pay Apple a yearly fee to sign the software; You're all going to have to put up with the following minor inconvenience:

When you launch Anathema for the first time after downloading it, you will see this message:

You can bypass this message by approving Anathema manually:

• Right click (or cmd+click) Anathema, and select Open.
• You will see this screen:
  
• Click Open
• Anathema is now authorized to run on your computer.