"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." Rom. 10:3 KJV

Ignorance is no excuse when the truth is readily available. Many of Paul's fellow Jews were sincere and zealous about keeping the old covenant of the Law and did not accept the truth that "Christ is the end of the Law for those who believe on Him." The Jews, in ignorance and unbelief, continued striving to merit their own personal righteousness. Sincerity is a corollary of truth, but never a substitute it. Many people are sincere, but sincerely wrong. The resurrection of Jesus Christ from the dead conclusively proves that He was God in human flesh and that ultimate truth resides with Him, not one's subjective opinion.