You cannot really know God until you rightly understand Genesis. That's a powerful claim, but one worth considering.
If God designed the Bible to consist of 66 books, and ensured that His revelation was complete and unified and without error in every word in those 66 books, then we must be careful not to dismiss any statement or any book that God divinely inspired for us to read and study.
God did not reveal His Word in a haphazard way; there is marvelous, perfect unity from beginning to end. Nor did God wait around to see what ancient peoples wrote before He inspired the writers of the Bible. The lordship, power, and omniscience of the triune God are plainly presented from the very first pages of Genesis.
Genesis 1:1 is clearly one of the greatest apologetics in all of Scripture, for if we stumble here, we cannot, or will not, appreciate God in the rest of the Bible. Accepting God as Creator demands our acceptance of Him as Judge, and that is exactly why many refuse to acknowledge that God exists, for doing so obligates them to deal with their sin before a righteous Judge.
Of course, this is not to say that one cannot know enough about God to receive His gift of salvation should one only know, for instance, a gospel presentation from the Book of John or Romans. Many millions have been saved with just portions of Scripture.
If Genesis doesn't matter - if God didn't want us to know Him through the book of Genesis - then He would have left it out of the Bible entirely.
(from Lawrence E. Ford, Three Reasons why Genesis Matters, Acts & Facts July 2011, Institute of Creation Research)