I also think that while Boolean expressions in Lisp are less natural than "this AND that OR another", they are clearer when they get large (with good formatting of course).

     1    +   2   *     3
    one plus two times three

     (*    (+  1   2)   3)
    times add one two three

So, "the product of the sum of 1 and 2, and 3"? Reads fine in English, as long as you refer to the results instead of describing what to do. :)

    (function1 (function2 1 2 3))

    function1(function2(1, 2, 3))

Of course 1 + 2 * 3 is more familiar that way, vs the Lisp way. But you have the Lisp way wrong (unless your example was Smalltalk)... it would be:

    (+ 1 (* 2 3))

Also, most math functions in Lisp are variadic. So if you have this in infix:

    x + y + z + 1
    // x plus y plus z plus one

    (+ x y z 1)
    ;; sum x y z and one

It might even be useful to give math operators new names in Lisp, because of the way that things like < > = == are a bit awkward when read as their equivalents in infix. They are all variadic, after all.

Compare:

    (x == 10 && y == 10) && (x < y && y < z && z < 100)

    (and (== x y 10) (< x y z 100))

    (all-true? (same? x y 10) (ascending? x y z 100))

    (apply < nums)

"Multiply the sum of 1 and 2 with 3".