There is some debate whether the Old Covenant is a saving covenant. It isn’t. Only the New Covenant saves, as it offers us forgiveness of sins through the shedding of Christ’s blood while the Old Covenant merely acts as a tutor (Gal 3:23) and points us to Christ.
The conversation was on Romans 9:30-32:
What shall we say then? That Gentiles, who did not pursue righteousness, attained righteousness, even the righteousness which is by faith; but Israel, pursuing a law of righteousness, did not arrive at that law. Why? Because they did not pursue it by faith, but as though it were by works.
She invoked this Scripture on the Pharisee and the Publican in response:
And He also told this parable to some people who trusted in themselves that they were righteous, and viewed others with contempt: “Two men went up into the temple to pray, one a Pharisee and the other a tax collector. The Pharisee stood and was praying this to himself: ‘God, I thank You that I am not like other people: swindlers, unjust, adulterers, or even like this tax collector. I fast twice a week; I pay tithes of all that I get.’ But the tax collector, standing some distance away, was even unwilling to lift up his eyes to heaven, but was beating his breast, saying, ‘God, be merciful to me, the sinner!’ I tell you, this man went to his house justified rather than the other; for everyone who exalts himself will be humbled, but he who humbles himself will be exalted.” (Luke 18:9-14)
She explained that the two men both had the Law. One used the Law as a means to attain righteousness by living by its commandments. In his self-deceit, he apparently believed that he was justified before God by his own effort. The Publican meanwhile saw the Law as a mirror in which to see himself for what he really was. He realized how far short he fell and how he had no hope, no matter how much he changed, to live by it. So, in faith, he called out to God knowing that only by His mercy and not by his own striving can he be saved.
The one who attained righteousness by faith went home justified. The one, pursuing a law of righteousness went home condemned.
There is no contradiction between the words of Jesus and Paul. May God remind us of this and keep in our minds how we are utterly powerless without His grace.