Does not the commandment state that we are not to make images of anything on earth?
"You shall not make for yourself a carved image, or any likeness of anything that is in the heaven above, or that is in the earth beneath, or that is in the water under the earth.
You shall not bow down to them or serve them for I the Lord your God am a jealous God," Exodus 20:4-5a (ESV) emphasis added.
The commandment prohibits making idols, regardless of what they look like. The key part of this passage is what is italized above, we are not to serve other masters. We know that making images of things other than God are acceptable, (provided they are not being worshiped of course), because of other passages where God commands His people to fashion images.
"And thou shalt make a candlestick of pure gold: of beaten work shall the candlestick be made: his shaft, and his branches, his bowls, his knops, and his flowers, shall be of the same. And six branches shall come out of the sides of it; three branches of the candlestick out of the one side, and three branches of the candlestick out of the other side: Three bowls made like unto almonds, with a knop and a flower in one branch; and three bowls made like almonds in the other branch, with a knop and a flower: so in the six branches that come out of the candlestick. And in the candlesticks shall be four bowls made like unto almonds, with their knops and their flowers."
Exodus 25:31-34 (ESV)
If you want a great brief treatment on this issue read Francis Schaeffers little book,
Art and the Bible, it is one of the best that I have ever read on the subject!
