Your first premise is false. Hooking up your sensory system to a device that generates the maximum signal would give a larger signal since it would bypass degradation in your mouth.
Think your argument through first. Are your premises actually true?
I am not aware of any claim that the devil is the largest evil that could be imagined. Further, such a definition would not make sense in for example traditional Christianity where evil is defined as a privation on good, not something that exists in itself.
Having God and the devil as evenly matched but opposite powers is not something you would find in theology. Learn the basics of it before thinking you have created a proper critique.
Think your argument through first. Are your premises actually true?