1. Know There is a God

The first commandment of Mosaic Law is to know there is a God.

Where in scripture?

From Exodus 20:2

"I, the LORD, am your God, who brought you out of the land of Egypt, that place of slavery."

New Testament references

Matthew 4:10 

"The Lord, your God, shall you worship" 

Catechism of the Catholic Church

2084 God makes himself known by recalling his all-powerful loving, and liberating action in the history of the one he addresses: "I brought you out of the land of Egypt, out of the house of bondage."

2085 The one and true God first reveals his glory to Israel. The revelation of the vocation and truth of man is linked to the revelation of God. Man's vocation is to make God manifest by acting in conformity with his creation "in the image and likeness of God":

2086 "The first commandment embraces faith, hope, and charity. When we say 'God' we confess a constant, unchangeable being, always the same, faithful and just, without any evil.

Atheism

2131 "Many . . . of our contemporaries either do not at all perceive, or explicitly reject, this intimate and vital bond of man to God. Atheism must therefore be regarded as one of the most serious problems of our time."

2124 The name "atheism" covers many very different phenomena. One common form is the practical materialism which restricts its needs and aspirations to space and time. Atheistic humanism falsely considers man to be "an end to himself, and the sole maker, with supreme control, of his own history." Another form of contemporary atheism looks for the liberation of man through economic and social liberation. "It holds that religion, of its very nature, thwarts such emancipation by raising man's hopes in a future life, thus both deceiving him and discouraging him from working for a better form of life on earth."

2126 Atheism is often based on a false conception of human autonomy, exaggerated to the point of refusing any dependence on God. Yet, "to acknowledge God is in no way to oppose the dignity of man, since such dignity is grounded and brought to perfection in God…"

Early Church Fathers

St. Justin, Dial. cum Tryphone Judaeo 11,1:PG 6,497

There will never be another God, Trypho, and there has been no other since the world began . . . than he who made and ordered the universe. We do not think that our God is different from yours. He is the same who brought your fathers out of Egypt "by his powerful hand and his outstretched arm."

Natural Law

Albert Einstein

"A knowledge of the existence of something we cannot penetrate, of the manifestations of the profoundest reason and the most radiant beauty - it is this knowledge and this emotion that constitute the truly religious attitude; in this sense, and in this alone, I am a deeply religious man."

Conclusion

Binding on Christians