Ryle, point 6 in his Warnings to the churches:
6. WHY THE DOCTRINE OF JUSTIFICATION BY FAITH ALONE WITHOUT WORKS IS IMPORTANT
“No man on earth is a real child of God, and a saved soul, till he sees and receives salvation by faith in Christ Jesus. No man will ever have solid peace and true assurance, until he embraces with all his heart the doctrine that ‘we are accounted righteous before God for the merit of our Lord Jesus Christ, by faith, and not for our own works and deservings.’ One reason, I believe, why so many professors in this day are tossed to and fro, enjoy little comfort, and feel little peace, is their ignorance on this point. They do not see clearly justification by faith without the deeds of the law.”
Ryle says that “many professors” are ignorant on the point of justification by the work of Jesus Christ apart from human effort as the sole ground of acceptance before God (cf. Romans 10:1-4). Now Ryle does say “professors” and not truly regenerate Christians. But in other writings he states the matter quite clearly:
“Finally, do not forget that assurance is a thing which may be lost for a season, even by the brightest Christians, unless they take care.
Assurance is a most delicate plant. It needs daily, hourly watching, watering, tending, cherishing. So watch and pray the more when you have got it. As Rutherford says, ‘Make much of assurance.’ Be always upon your guard. When Christian slept in the arbor, in Pilgrim’s Progress — he lost his certificate. Keep that in mind” (J.C. Ryle, Holiness).
Thus Ryle is saying that it is possible for a truly regenerate person to be “ignorant of the righteousness of God, and [seek] to establish their own righteousness” (Romans 10:3). Let God be true, and Ryle a liar.