Adam Clarke on Romans 3:23

For all have sinned : - And consequently are equally helpless and guilty; and, as God is no respecter of persons, all human creatures being equally his offspring, and there being no reason why one should be preferred before another, therefore his endless mercy has embraced All.

And come short of the glory of God - και υστερουνται της δοξης του θεου These words have been variously translated. Failed of attaining the glory of God: Have not been able to bring glory to God: Stand in need of the glory, that is, the mercy of God. The simple meaning seems to be this: that all have sinned, and none can enjoy God's glory but they that are holy; consequently both Jews and Gentiles have failed in their endeavors to attain it, as, by the works of any law, no human being can be justified.