That isn't what was happening in Paul's Time. I hear these falsehoods promoted over and over and over. But that isn't the Attitude Paul was fighting at all.
Both Jesus and Paul were placed by God into a religious system that;
Mark. 7:9
And he said unto them, Full well ye "reject the commandment of God", that ye may keep your own tradition.
A religious sect who
professed to know God, "
Who have received the law by the disposition of angels, and have not kept it." (Acts 7:53)
A religious business selling forgiveness in the form of turtle doves and goats, who Jesus said "
Did not Moses give you the law, and yet none of you keepeth the law? Why go ye about to kill me?
A religious sect that Paul said:
Rom. 10:
3 For they being ignorant of God's righteousness, and going about to establish "their own righteousness", have "not submitted themselves" unto the righteousness of God.
And yet Mainstream Christianity rejects "EVERY" Word of Jesus and the Law and Prophets, and Paul concerning the practices of the religious sect of the Pharisees based on a single sentence from Paul, "Not having my own righteousness, which is by the Law".
Refusing to accept or even consider that according to the Old Priesthood that the Pharisees were promoting their own version of, Sins can only be forgiven by taking a goat to the Levite Priest. A temporary Law "Added" because of Transgressions, Till the Seed, (The True Lamb of God) should come.
So according to what is actually written in the Holy Scriptures, the mainstream religion of Jesus and Paul's Time, wasn't trying to "Earn Salvation" by obeying God's Laws, "to the letter", as the deceivers of this would have us believe. They were promoting a Salvation through the religious philosophies and Traditions and Commandments of men, that Jesus Himself said they taught for Doctrines.
This is confirmed in many places, but one glaring example of the deception that the Pharisees were trying to earn salvation by obeying God's Laws is in Luke 1 & 2.
Luke 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. 6 And they were both righteous before God, walking in all the commandments and ordinances of the Lord blameless.
Now, what "doctrine" did Zacharias promote?
67 And his father Zacharias was filled with the Holy Ghost, and prophesied, saying,
Why was this, according to the New Testament teaching?
Acts 5:
32 And we are his witnesses of these things; and so is also the Holy Ghost, "whom God hath given" to them "that obey him". So this is why Zacharias received the Spirit of Truth, while the Pharisees didn't.
68 Blessed be the Lord God of Israel; for he hath visited and redeemed his people, 69 And hath raised up an horn of salvation for us in the house of his servant David; 70 As he spake by the mouth of his holy prophets, which have been since the world began:
So EG, according to what is actually written in the Bible, the Pharisees were NOT trying to earn God's favor by being a "Doer" of His Instruction, rather, they had created their own religion, with their own judgments, their own philosophies and traditions, even their own high days. Had they Loved God, and trusted God, "in Faith" like Zacharias, Simeon, Anna, the Wise Men, Caleb, David, Shadrack, Cornelious, Paul and all examples of Faithful men given to us in Scriptures, they would have known Jesus when HE came, just as Zacharias, Simeon and Anna all knew Jesus, before HE was even born.
Jesus warned of religious men who call Jesus Lord, Lord, who "come in His Name", and Paul warned specifically of men who "Transform themselves" into Apostles of Christ, that we are not deceived by them. The popular religious philosophy, promoted by "many" who call Jesus Lord, Lord, that the Pharisees were trying to "Earn Salvation" by obeying God's Law is an insidious falsehood, created by the prince of this world to demean God and His Instruction in Righteousness. Do the Study yourself, in Faith, and you will find the same Truth.