I form the light, and create darkness: I make peace, and create evil: I the LORD do all these things. King James Bible
All other translations read ‘and cause calamity’ instead of ‘and create evil’. I kinda feel the King James version gets that shocking word evil wrong enough in our modern, glancing interpretation that we should take pause and gain a better understanding of what God does and doesn’t do- especially in His relationship to evil. This is the paramount purpose of these writings compiled in the Bible. And God is outright telling us ‘who He is’ in this very verse so let’s get this right.
Darkness is where those who choose evil end up going. Thus celestial darkness -which the bible often refers to- is not evil itself. Though it certainly is the absence of light and in the context here it would be the absence of God’s Light. I would assume it IS dark- darker than we can fathom. Science says the hottest heat they can create hypothetically is in complete darkness. Anyone in this hot darkness would undoubtedly be weeping and gnashing their teeth.
Is God absent in the dark forest at night? No. But He did create that darkness as well. I don’t think the link between our physical darkness and that celestial darkness are too far related. In the same sense that He creates darkness by His absence in both realms.
Hebrew for evil is the key to understanding what is being said. The word in that text is ‘ra’ meaning bad, evil, calamity. Grammatically in Isaiah 45:7 ra is a verb so it falls into the calamity side of it’s meaning in context.
His willfull absence as humanity progresses creates spiritual darkness wherein calamity happens around us, to us, and by us in its myriad instances. Our sin separates us from God Isaiah also says. This mathematically equates to darkness. Has Christ overcome this darkness? He certainly has. But what about the evil calamity of darkness we see taking shape and moving in the world around us? His absence allows that evil action to render consequences in all its ways. Though that patchwork of darkness is allowed only to take shape and manifest toward His end result.