What Genesis 1:1 establishes
The opening verse introduces God as already present “in the beginning” and identifies Him as the Creator. The heaven and the earth express the created order in its entirety.
Genesis begins with God rather than attempting to explain His origin. The remainder of the chapter describes God ordering and filling creation by His word.
First words, verse, and sentence
In the KJV, “In the beginning” are the first three words. Genesis 1:1 is the first verse, and its complete wording is the first sentence. The opening is echoed in John 1:1, which begins, “In the beginning was the Word.”