Thou art righteous - Thou art merciful; this is one of the many meanings of the word צדק tsedek; and to this meaning St. Paul refers, when he says, God declares his righteousness for the remission of sins that are past, Rom 3:25 (note). See the note there.
We remain yet escaped - Because of this righteousness or mercy.
In our trespasses - We have no righteousness; we are clothed and covered with our trespasses.
We cannot stand before thee because of this - The parallel place, as noted in the margin, is Psa 130:3 : If thou, Lord, shouldest mark iniquities, O Lord, who shall stand? Every man must stand before the judgment-seat of Christ: but who shall stand there with joy? No man against whom the Lord marks iniquities. There is a reference here to the temple service: the priests and Levites stood and ministered before the Lord, but they were not permitted to do so unless pure from all legal pollution; so no man shall stand before the judgment-seat of Christ who is not washed and made white in the blood of the Lamb. Reader, how dost thou expect to stand there?