1 Timothy 6:13-16
13 In the presence of God, who gives life to all things, and of Christ Jesus, who in his testimony before Pontius Pilate made the good confession, I charge you14 to keep the commandment without spot or blame until the manifestation of our Lord Jesus Christ, 15 which he will bring about at the right time—he who is the blessed and only Sovereign, the King of kings and Lord of lords. 16 It is he alone who has immortality and dwells in unapproachable light, whom no one has ever seen or can see; to him be honor and eternal dominion. Amen.
There are so many places in scripture that speak of God as a "blinding light." What could this mean? Isn't God supposed to be loving and approachable? Why would God be described here as "unapproachable?"
I think the best way to understand these passages is to understand that while we usually want God to conform to the limited way that we see the world, God wants us to conform to Him. We only see a very small part of reality, and we only see that small part in a partial and incomplete sense. In contrast, God sees all that is, fully and completely. Passages like this one remind us that it isn't God that needs to change so that we can fully understand Him. Rather, we need to develop into the kind of people that can see God more clearly.
This requires work and discipline and this is where our spiritual lives come up. The traditional practices that develop our ability to "see" God's reality haven't changed; prayer, worship, reflection, and devotion all help to sharpen our focus and mold us into the kind of people that can better relate to our unseen God. God may never be completely approachable for us, but we can get a lot better at seeing God's will through the right kinds of practices.