Genesis 1:1 In the beginning God created the heaven and the earth.
The very first verse in the Bible is sort of like a chapter “spoiler” — it tells you what is about to happen, but it hasn’t happened yet. This will be made clear shortly.
2 And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.
The conditions at the beginning of the world were thus: It was dark, there was nothing but water everywhere, and God’s spirit moved around in it. It doesn’t say that God created the water, for all we know it the water is co-eternal with God.
3 And God said, Let there be light: and there was light.
In this verse God performed his first act of ex nihilo creation, or something from nothing. Now there was light to see, but water was the only matter which existed, with nothing in the water to see with the light, not even a surface with waves.
4 And God saw the light, that it was good: and God divided the light from the darkness.
Next God performed his first act of judgment, he separated the light from non-light. All through the Sacred Scriptures God will repeat this same act of screening or filtering, more often with people.
5 And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.
Now it was Sunday night but there was no sun yet. All we had was a time when it was light, and a time when it was dark. That tells us God separated the light and darkness by intervals of time.
6 And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
A firmament is a solid dome or vault. This dome was God’s second act of ex nihilo creation, created on Monday morning.
7 And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.
The purpose of the solid dome was to divide the water that was, at that point, everything, into two separate reservoirs, upper and lower.
8 And God called the firmament Heaven. And the evening and the morning were the second day.
Only on Monday did God call the firmament or dome “heaven”. That is why verse one is not when God created the heavens and earth but only a chapter heading.