Those who grope around in darkness (see Deut. 28:29) cannot praise Jehovah for they see Him not. Light in the context of Genesis 1, John 1, and myriads of other verses says to believers that if they want to understand the world around them, be at peace, and receive all the goodness which comes to the those who love the Lord than they best be abiding in the light and seeking out the light wherever He may be found.
There is a call to love the light that reverberates throughout the Bible. The marking out of darkness as the realm of evil is an image which is meant to evoke for us the vanity of seeking after wicked things, for they lead us astray from the good and they actively take us away from the truth. Darkness has always, in every culture, been the domain of the dead. Your grandaddy’s old saying that nothing blessed happens after midnight has been shared by old men to their progeny in Romania as much as Mongolia. It is a universal knowledge. It is part of the reason why the color black is the shade chosen by those who which to be seen as transgressive, non-conformist, and those who wish to let everyone know they mean trouble. The silver and black of the Raiders was chosen on purpose.
In the beginning (no pun intended) when we are first introduced to our God it is mentioned that darkness was on the face of the deep. The Holy Spirit is seen hovering over the waters. Then God makes light which comes neither from the sun nor the moon, but from the command of His voice. Why was it made? It is not as if the Third Person of the Holy Trinity needed it to see. Our God does not have eyes like men. Also darkness isn’t meant to imply the absence of God, and light the presence of God (more on that in a minute). It can seem as if there is a deeper thing going on here that we are not quite ready to comprehend completely, especially if you are coming to Genesis with preconceived notions of what to expect. However, as we think about what the Lord is doing we need to remember that as the patriarchs gave us testimony, they knew that one was to come who would give light to the answers we seek.
The Apostle John as he writes his gospel will mimic these opening words of Genesis and apply them directly to Jesus Christ. He writes:
In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things were made through Him, and without Him nothing was made that was made. In Him was life, and the life was the light of men. And the light shines in the darkness, and the darkness did not comprehend it.