Why would an omnipotent God, who could speak creation into existence, take a whole six days to do so? Some of the early church fathers therefore believed that God created every- thing in only one day, or in an instant. To counter this teaching, Martin Luther wrote: “When Moses writes that God created heaven and earth and whatever is in them in six days, then let this period continue to have been six days, and do not venture to devise any comment according to which six days were one day. But, if you cannot understand how this could have been done in six days, then grant the Holy Spirit the honor of being more learned than you are. For you are to deal with Scripture in such a way that you bear in mind that God Himself says what is written. But since God is speaking, it is not fitting for you to wantonly turn His Word in the direction you wish it to go.”
“So far as I know, there is no professor of Hebrew or Old Testament at any world-class university who does not believe that the writer(s) of Genesis 1–11 intended to convey to their readers the idea that (a) creation took place in a series of six days which were the same as the days of 24 hours we now experience; (b) the figures contained in the Genesis genealogies provided by simple addition a chronology from the beginning of the world up to later stages in the biblical story; (c) Noah’s Flood was understood to be worldwide and extinguish all human and animal life except for those in the ark.” Dr. James Barr, professor of Hebrew, Oxford University
Exodus 31:17 It is a sign between Me and the children of Israel forever; for in six days the Lord made the heavens and the earth, and on the seventh day He rested and was refreshed.