Exodus 12:40 Now the sojourning of the children of Israel, who dwelt in Egypt, was four hundred and thirty years.
41 And it came to pass at the end of the four hundred and thirty years, even the selfsame day it came to pass, that all the hosts of the LORD went out from the land of Egypt.
In trying to reconcile the Biblical calendar, some theologians of the past have concocted a doctrine that flatly goes against the Word of God's declaration above that the children of Israel were 430 years to the selfsame day in the land of Egypt. The theologians say that the 430 years started with Abram as he came into the land of Canaan. They then go on to conclude that Israel was only actually 215 years in the land of Egypt, as the other 215 years, they say, was from the point of Abram's entry into Canaan until Jacob took his family into Egypt.
With doctrines like this, is it any wonder that the wrath of God came down upon the congregations because of their high places? Although, regarding the theologians of the past, we do have to make some allowances since they were operating at a time when the Lord had sealed up the Biblical calendar of history for the most part. It wasn't until the 1970's or so, that the Lord began to open up the eyes of Mr. Camping to unlock the calendar primarily found in the genealogies of the book of Genesis.
But some today do not have the excuse for their ignorance of the Bible's timeline for history. They've heard about the Biblical calendar and have rejected it in their blindness. Therefore it is a far worse sin for those people today who brazenly reject the Bible's straightforward declaration that the children of Israel were in Egypt for 430 years to the very day. What tremendous arrogance and pride it takes for men to contradict the Word of God in this manner.