The concept of Lucifer's flood is part of the "gap theory" of origins, which postulates a time spanning millions of years that came before the six-day creation but after God's initial creation of the heavens and the earth. Genesis 1:1 says, "In the beginning, God created the heavens and the earth." Genesis 1:2 says "The earth was without form and void, and darkness was over the face of the deep. And the Spirit of God was hovering over the face of the waters." The gap theory inserts millions of years into the "gap" between Genesis 1:1 and 1:2, in an attempt to allow for geological discoveries such as the fossil record, and to make the Bible appear more plausible to modern minds.
What is the concept of Lucifer's flood? Is the idea of a Luciferian flood biblical?
Part of the gap theory is the idea of Lucifer's flood, also called the Luciferian flood, a time when Satan ruled the earth, and when the earth was peopled by soulless men. During this time, say gap theorists, the rebellion of Satan occurred and God punished him by bringing a flood. The idea is that all the fossil records come from the millions of years before this flood, and the six-day creation happened afterward, when the earth was "without form and void." There are some problems with gap theory and Lucifer's flood.
Lucifer's flood and the gap theory are pure speculation. If we believe the Bible to be literally true, it is unsupportable to simply insert things like Lucifer's flood or the millions of years in the "gap" for the purpose of making sense of scientific theories and geological discoveries. The fact is, those discoveries are not explained in the Scripture, and there is likely a very good explanation for their existence, but we don't know what it is.
Furthermore, when God judged Satan and destroyed the earth with a flood, to the degree that it was "without form and void" afterward, why was the fossil record not also destroyed? "Without form and void" seems to indicate that there was literally nothing left. Finally, the book of Genesis is clear that death was a result of the sin of Adam and Eve, and that "sin came into the world through one man, and death through sin" (Romans 5:12). If we believe that this is true, how can we also believe that death occurred before the fall, during the events of the supposed Lucifer's flood?
Gap theory and the Lucifer's flood theory depend on a lot of speculation, and on the physical evidence brought by science. It is an attempt to explain and understand why the Bible and the scientific record do not agree in terms of the age of the earth. We do not know the answer to this. Maybe, someday, we will. But for now, when the two disagree, we have to choose whether to believe God's Word or to believe the empirical evidence brought by scientists. It may be difficult for us to trust God when presented with supposedly unshakable evidence of something that contradicts the Scripture, but faith is "the conviction of things not seen" (Hebrews 11:1). In any case, it is not a good idea to come up with theories based entirely on speculation that have no basis either scientifically or biblically.
The Gap Theory – What is it? Did anything happen in between Genesis 1:1 and 1:2?
Does the Bible mention prehistoric men such as cavemen or Neanderthals?
If God knew the Fall was going to happen – that Satan would rebel and Adam and Eve would sin – why did He create them?
Do Genesis 1 and 2 record two different creation accounts?
Was the Noahic flood global?
Truth about Creation