From the Wikipedia article on Pyramidology:
Pyramidology is a term used, sometimes disparagingly, to refer to various pseudoscientific speculations regarding pyramids, most often the Giza Necropolis and the Great Pyramid of Giza in Egypt.
Pyramidology is regarded as pseudoscience by scientists today, who regard such hypotheses as sensationalist, inaccurate and/or wholly deficient in empirical analysis and application of the scientific method.
Some pyramidologists claim that the Great Pyramid of Giza has encoded within it predictions for the exodus of Moses from Egypt, the crucifixion of Jesus, the start of World War I, the founding of modern-day Israel in 1948, and future events including the beginning ofArmageddon; discovered by using what they call "pyramid inches" to calculate the passage of time (one British inch = one solar year).
Charles Taze Russell
In 1891 pyramidology reached a global audience when it was integrated into the works of Charles Taze Russell, founder of the Bible Student movement. Russell however denounced the British-Israelite variant of pyramidology in an article called The Anglo-Israelitish Question . Adopting Joseph Seiss's designation that the Great Pyramid of Giza was "the Bible in stone" Russell taught that it played a special part in God's plan during the "last days" basing his interpretation on Isaiah 19:19-20 which says - "In that day shall there be an altar (pile of stones) to the Lord in the midst of the land of Egypt, and a pillar (Hebrew "matstebah" or monument) at the border thereof to the Lord. And it shall be for a sign, and for a witness unto the Lord of Hosts in the land of Egypt." Two brothers, archaeologists John and Morton Edgar, as personal associates and supporters of Russell, wrote extensive treatises on the history, nature, and prophetic symbolism of the Great Pyramid in relation to the then known archaeological history, along with their interpretations of prophetic and Biblical chronology. They are best known for their two-volume work Great Pyramid Passages and Chambers, published in 1910 and 1913.
Although most Bible Student groups continue to support and endorse the study of pyramidology from a Biblical perspective, the Jehovah's Witnesses, who emerged from the original Bible Student Movement in 1931, have abandoned pyramidology entirely.