Galatians 3:19-24King James Version (KJV)
19 Wherefore then serveth the law? ( ceremonial not the ten ) It ( ceremonial )was added because of transgressions, till the seed should come to whom the promise was made; and it was ordained by angels in the hand of a mediator.
20 Now a mediator is not a mediator of one, but God is one.
21 Is the law then against the promises of God? God forbid: for if there had been a law given which could have given life, verily righteousness should have been by the law.
22 But the scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe.
23 But before faith came, we were kept under the law ( ceremonial ), shut up unto the faith which should afterwards be revealed.
24 Wherefore the law (ceremonial )was our schoolmaster to bring us unto Christ, that we might be justified by faith.
in verse 19, it says that the law was ADDED because of transgression. Now if this is also talking about the ten commandments, the moral law of God, then what was it ADDED to? There is nothing to add it to.
But if we take this verse in truth and apply it to the ceremonial laws and the priestly service, then it makes sense. The ceremonial laws were ADDED to the ten commandments, BECAUSE OF SIN AGAINST THE TEN COMMANDMENTS. Do you see this? So then, the "schoolmaster" is the priestly service, containing the ceremonial laws, which pointed to Christ Jesus, as He became our sacrifice for sin, and our High Priest.