The Gap Theory of Evolution was developed in the 19th century by theologians as a compromise theory to fit millions of years of theoretical evolution into the straight forward history of the universe as recorded in Genesis 1-2. It is an attempt to harmonize the Biblical facts with ideas proposed by fallible men.
Basically, some Christians try to shoehorn millions of years in between Gen. 1:1 and Gen. 1:2. As will be seen, when you add millions of years of evolution to the Genesis history you destroy the authority of the Bible as well as the reason for Christ’s sacrifice. (You can see the details of this analysis at this post.)
Since this theory is a bit complicated I thought it would be reasonable to simply collect some of the best Gap Theory articles from the web and summarize them here:
Mind the Gap-by Monty White
“Although there are variations, the basic teaching of the gap theory is that millions of years ago God created the universe and everything in it as recorded in Genesis 1:1. Sometime during the subsequent millions of year, Lucifer (i.e., Satan) rebelled and was thrown to earth. This resulted in Lucifer’s Flood, which destroyed all plant and animal life on earth, thus producing the fossil record in the rock layers.
The gap theory is simply compromise. This relatively modern theory has been formulated in the last couple hundred years in an attempt to harmonize the facts of Scripture with the ideas of fallen men. This compromise view is designed to accommodate those who believe in millions of years. Proponents of the gap theory have reinterpreted Scripture to try to make it fit the idea of millions of years. The gap theory does not rest upon the impregnable rock of Holy Scripture but is founded upon the shifting sands of the ideas of those who want to believe the evolutionary teaching of millions of years. No wonder we should mind the gap.” (read more)
“A simple, straightforward reading of the biblical record indicates that the Cosmos was created in six days only a few thousand years ago. Opposed to that view is the idea of evolutionists that the Universe is probably 15-20 billion years old, and that the Earth is as much as 4.6 billion years old. Further complicating matters is the fact that the biblical record indicates living things were placed on the newly created Earth even before the end of the six-day creative process (e.g., plant life came on day three). The evolutionary scenario, however, postulates that primitive life evolved from nonliving chemicals roughly 3.5-4.0 billion years ago, and that all other life forms developed during the so-called geologic ages, with man arriving on the scene in one form or another 1-2 million years ago.
Popularity of the Gap Theory is generally attributed to the writings of Thomas Chalmers, a nineteenth century Scottish theologian. In recent years, the Gap Theory has undergone an “evolution” of its own, and for that reason is not easily defined. There are several variations, and its defenders do not agree among themselves on strict interpretations. However, a brief summation of its main tenets might be as follows….”(read more).
“However, many of those who hold to the gap theory do so in order to reconcile old-earth, evolutionary theories with the book of Genesis. But it seems to be a strained reconciliation. The plain reading of Genesis 1 does not at all intimate a length of time between the first two verses. Genesis 1:1 tells us that God created the heavens and the earth. Genesis 1:2 informs us that, when He first created the earth, it was formless, empty, and dark; it was unfinished and uninhabited. The rest of Genesis 1 relates how God completed the formless, empty, and dark earth by filling it with life, beauty, and goodness.” (read more)
(This short article summarizes most of the compromise theories regarding Genesis history and evolution.)
“Old Earth Creationism is an attempt to reconcile the idea that the earth is billions of years old with the creation account of Genesis 1. Some versions take the Bible and try to interpret the Scriptures to determine a place for the fossil record and Neanderthals and dinosaurs. Others start with the science and try to fit God as Creator into evolution. The problem with old-earth creationism, beyond forcing the seven-day creation account into a world so old, is in Romans 5:12: “Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned.” This passage clearly shows that death entered the world through Adam’s sin. If that’s the case, how could any animal have died before Adam? Different theories have their own “end-arounds.” Please keep in mind that the mechanism of the development of life on earth is not a salvation issue; there are many faithful believers on all sides of the issue. But it is a good idea to get a general idea of the arguments.” (read more)