A comprehensive study of the law of God requires a deeper understanding of the context in which the law is couched in divine revelation. It is vital for us to consider how the commandments are presented and applied in both the Old Testament and the New Testament. The moral law is the basis of the Mosaic law, but the two cannot be confused. Christians and all of God’s intelligent creatures are under His eternal moral law, but only Israel was ever under the Mosaic pattern of the moral law (De. 6:4-6). The simplest way to demonstrate this conclusion is to examine the Mosaic Ten Commandments and compare them to their restatement in the New Testament.
“Thou shalt have no other god’s before me” (Ex. 20:3). The penalty for the violation of this first law was death. Later in Exodus 22:20 God says, “He that sacrificeth unto any god, save unto the Lord only, he shall be utterly destroyed.” This first command is foundational to our relationship with God. F.D. Coggan summarizes, “To seek to produce Christian ethics apart from the first commandment, character apart from religion, is like trying to produce roses from a tree whose roots have been cut, or to rear a noble building when the foundations have been neglected or undermined.” To glorify God means, as one author put it, to emphasize the “firstness” of Jehovah God.
The first commandment is not repeated verbatim in the New Testament but the principle is emphatically validated. “For there is one God and one mediator between God and man, the man Christ Jesus” (I Timothy 2:5). Before the polytheistic worshippers of Lystra, Paul declared, “We are also men of like passions with you, and preach unto you that ye should turn from these vanities unto the living God, which made heaven, and earth, and the sea, and all things therein” (Ac. 14:15). James adds this perspective, “Thou believest that there is one God; thou doest well: the devils also believe, and tremble” (Ja. 2:19). It is important to note that nowhere in the New Testament is the Mosaic penalty of death either affirmed or implied. The first commandment has been annulled, but the moral principle that Jehovah God alone should be worshiped and served continues forever.
Here are just a few specific areas to put God first:
1. In Your Love
Mt 22:37 “Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind.”
2. In Your Day
Ps 63:1 “O God, thou art my God; early will I seek thee: my soul thirsteth for thee, my flesh longeth for thee in a dry and thirsty land, where no water is;”
3. In Your Week
Jn 20:19 “Then the same day at evening, being the first day of the week, when the doors were shut where the disciples were assembled for fear of the Jews, came Jesus and stood in the midst, and saith unto them, Peace be unto you.”
4. In Your Giving
I Co. 16:2 “Upon the first day of the week let every one of you lay by him in store, as God hath prospered him, that there be no gatherings when I come.”
Can you think of other specific moral applications of the first commandment for the NT believer?
 F. D. Coggan, The New Testament Basis of Moral Theology (London: Tyndale, 1948), 3.