Difference between "May" and "Let" in biblical language

Solution 1:

For each of your examples, the better word of the two is may, in my opinion.

Let and may seem similar in meaning (and to some extent, they are), but they are used in slightly different ways.

In the context of biblical content, let brings to my mind the old-fashioned use of the word let, which implied that a hindrance or obstacle must be removed. A common phrase in "legalese" is: "without let or hindrance" (meaning obstacle).

Therefore, when let appears in a biblical text, it can mean to allow, implying there should be no obstacle, as in the words of Jesus:

Let not your heart be troubled. Ye believe in God; believe also in me (John 14:1).

In other words,

Do not allow your heart to be troubled . . ..

Or,

Allow your heart to be un-troubled . . ..

On the other hand, in biblical content, the word may does not carry with it the idea of an obstacle; rather, it implies there is no obstacle, so

This is how it ought to be, or this is how it should happen . . ..

So instead of saying

May praise be to the God and Father of our Lord Jesus Christ,

you could say

This is what should happen: Praise [should be] to the God and Father of our Lord Jesus Christ.

As Rob Ster, above, aptly said, "May seems to imply a wishful benediction, while let . . . feels like 'fiat,' [as in] 'Let there be light.'"