Robert is surely correct in saying that God never changes.
However, the way He in which He deals with humanity has changed.
The Old Covenant and the Law of Moses were for a specific purpose in God's plan. They served their purpose and are now obsolete.
- In that He says, “A new covenant,” He has made the first obsolete. Now what is becoming obsolete and growing old is ready to vanish away (Hebrews 8:13, NKJV).
What was that purpose?
Because of Jesus and the New Covenant, we are no longer under the bondage of days and confusing calendars:
- "Before faith came, we were kept under guard by the law, kept for the faith which would afterward be revealed. Therefore the law was our tutor to bring us to Christ, that we might be justified by faith. But after faith has come, we are no longer under a tutor" (Galatians 3:23-25).
Therefore, "Stand fast therefore in the liberty by which Christ has made us free, and do not be entangled again with a yoke of bondage" (Galatians 5:1).
- "After you have known God, or rather are known by God, how is it that you turn again to the weak and beggarly elements, to which you desire again to be in bondage? You observe days and months and seasons and years. I am afraid for you, lest I have labored for you in vain" (Galatians 4:9-11).