All have sinned, so how do you explain this?
Luk 1:5 There was in the days of Herod, the king of Judaea, a certain priest named Zacharias, of the course of Abia: and his wife was of the daughters of Aaron, and her name was Elisabeth.
Luk 1:6 And they were both righteous before God, walking in all the commandments and ordinances of the Lord blameless.
It doesn't say that their righteousness derived from 'walking in all the commandments'. They were credited or declared righteous the same way all mankind has been found righteous going all the way back to Abel, and that is through faith in the promises of God. They looked forward to the promised Messiah.
'All have sinned' still stands because if judged in their own righteousness they would have been found wanting.
Finally, my brethren, rejoice in the Lord. To write the same things to you, to me indeed is not grievous, but for you it is safe. Beware of dogs, beware of evil workers, beware of the concision. For we are the circumcision, which worship God in the spirit, and rejoice in Christ Jesus, and have no confidence in the flesh. Though I might also have confidence in the flesh. If any other man thinketh that he hath whereof he might trust in the flesh, I more: Circumcised the eighth day, of the stock of Israel, of the tribe of Benjamin, an Hebrew of the Hebrews; as touching the law, a Pharisee; Concerning zeal, persecuting the church;
touching the righteousness which is in the law, blameless. But what things were gain to me, those I counted loss for Christ. Yea doubtless, and I count all things but loss for the excellency of the knowledge of Christ Jesus my Lord: for whom I have suffered the loss of all things, and do count them but dung, that I may win Christ,
And be found in him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith:
(Php 3:1-9)
Zacharias and his wife would agree with Paul.