Deuteronomy chapter 4

vs 11

Again, using a communal historical memory here. Although it could be, (though I've never heard it argued) that those who were already too old to fight didn't die in the desert. In any case, this is certainly a memory they should continue - the fiery mountain where God gave them the commandments.

vs 12

If you've ever wondered if they saw a form, there's your answer. Now we might be somewhat used to this, with loudspeakers and radios and such. But imagine being a copper aged culture, and seeing a mountain on fire and hearing a loud voice. There's no special effects back then.

vs 13

This actually happened to Moses if I recall. But hey, he passed on the memory to them. It's theirs now.

vs 14

Moses has a lot of responsibilities as a leader. Teach them the law and how to obey it, judge between the people, raise up a new leader for them for when he dies, continually remind them of these things. S'lonely at the top, especially since Aaron died, no doubt.

vs 15-18

Because God is formless, they are not to make idols. I don't know how much I could say on all these verses individually. Basically, don't make an idol of anything. Because if you do, it's obviously not God you're worshipping, because you never saw him! Now, what if they made idols of burning bushes or pillars of flame? It does say "any shape" at the beginning, I suppose. But it's interesting that the assumption is that an idol will be made to look like something alive.

vs 19

I find it interesting that reasonable statements are accompanying each of these warnings. Don't worship idols - why? Because you never saw God take a form. Don't worship the heavenly array - why? Because God shares them with everyone, they're not specifically yours.

vs 20

And while God isn't specifically theirs either, they are specifically God's. And that brings with it responsibility in worship.