D&C 74

As I have studied Church history and the Doctrine and Covenants, the more I have the opinion that the Lord commanded the Prophet Joseph Smith to translate the Bible for the sole intent that as the Prophet pondered the words of the Bible, which did cause many questions, allowed the Prophet to approach the Lord for answers and interpretations which brought much of the modern revelations.

We find this again as the Prophet read the writing of Paul -

"For the unbelieving husband is sanctified by the wife, and the unbelieving wife is sanctified by the husband: else were your children unclean; but now are they holy."  (New Testament | 1 Corinthians 7:14)

From the teachings of Mormon, the Prophet already knew that little children cannot sin and are saved through the atonement of Christ.  Yet, Paul wrote that some of the Corinthian's children were unclean which was a Jewish belief.  Obviously, this brought the Prophet to inquire of the Lord.  The Lord explained -

"...in the days of the apostles the law of circumcision was had among all the Jews who believed not the gospel of Jesus Christ."  (Doctrine and Covenants | Section 74:2)

Thus -

"...the children, being brought up in subjection to the law of Moses, gave heed to the traditions of their fathers and believed not the gospel of Christ, wherein they became unholy."  (Doctrine and Covenants | Section 74:4)

Or as they grew to ages of accountibility, they refused to follow the teachings of the gospel of Jesus Christ.  This is why -

"...for this cause the apostle wrote unto the church, giving unto them a commandment, not of the Lord, but of himself, that a believer should not be united to an unbeliever; except the law of Moses should be done away among them,
6 That their children might remain without circumcision; and that the tradition might be done away, which saith that little children are unholy; for it was had among the Jews..."  (Doctrine and Covenants | Section 74:5 - 6)

Not that circumcision is unholy or a sin, but that reliance only upon the law of Moses would lead the children away from Christ.  The Lord then states again the truth -

"...little children are holy, being sanctified through the atonement of Jesus Christ..."  (Doctrine and Covenants | Section 74:7)