Sometimes I've tried to side-step this problem. I have said something like "if you'd been in Palestine in the early first century AD, you could have seen God face to face". And I think that's true, theologically and historically. If you had come face to face with Jesus Christ, you would have seen God.
But recently I've become profoundly uncomfortable with that answer, and I don't think I'll give it anymore. Because another question has come up in my mind.
Was God ever more invisible than when he was the man of sorrows? Was the invisibility of God ever more evident than at Golgotha - a felt invisibility, like a shadow, or a dark spot where you know you should be able to see something?
Might the invisibility of God be a vital part of life on this side of the day when I will see him as he is? Might the only visibility available to us now be that by the Spirit's power, through faith and not sight, we can "see" the glory of God in the face of Jesus Christ?