## outwardly ##

This refers to Jewish rituals which people can see.

## outward ##

This is the physical evidence on his genitals that a man has received circumcision.

## he is a Jew who is one inwardly, and circumcision is that of the heart ##

This is a doublet in which "he is a Jew who is one inwardly" explains the metaphor "circumcision is that of the heart."

## inwardly ##

This refers to the values and motivations of the person whom God has transformed.

## in the spirit ##

This probably refers to the internal, spiritual part of a person, in contrast to the outward "letter" of the Law. However, it is also possible that it refers to the Holy Spirit (see UDB).

## not in the letter ##

A “letter” is the smallest part of written language. Here it refers to written Scripture. Alternative translation: “through the work of the Holy Spirit, not because you know the scriptures.” (See: [[rc://en/ta/man/translate/figs-synecdoche]])