One thing that used to bother me in reading the Old Testament is that the Israelites kept switching from following God to the gods of the day, Baal, Ashtoreth, and others. Another typical reaction, other than "Why?" is that as they turned from God they started going downhill. Soon, they realized it, turned back, and He blessed them all over again. In many ways reading some of the books of the Bible are like watching a scary movie. We find ourselves screaming at the screen saying, "Look behind you! Have you never seen a scary movie?"
Typically speaking, we gloss over the law especially as it relates to the part of the law we no longer practice. Sacrifice a bull for this, a goat for that, two birds for this. Only clean animals without blemish, sprinkle the blood here, burn the fat there. When you start to think about what the temple looked like, it had to be a bloody, sticky, gooey mess. And the tabernacle was a bloody, sticky, gooey, portable mess. It was like a slaughterhouse floor at times. The gods that the Israelites periodically switched to follow had similar rituals. They had graven images, idols, statutes and didn't care if the animals were clean, unclean, or human, but their altars were just as bloody, sticky, gooey and all around messy.
There are some places in the world where no matter what religion you follow, or even if you don't follow one, just seem to exude holiness. Granted, some more than others. The Dome of the Rock in Jerusalem is one. Any of the medieval cathedrals, and many of the cathedrals in the US demand respect. You don't walk in and sit down talking on their cell phone. Even if you don't follow that denomination there is a hushed reverence, like a library on steroids. This is more so in the highly organized or structured denominations/religions. And yes, some has to do with what you believe in. A Catholic in a cathedral is more reverent than a Baptist. Daddy Byrd, when he worked at the Church of the Redeemer, would bow toward the altar when he crossed the nave of the church, even when he was working. To a lesser degree, that is why I can't text or Twitter in our sanctuary while the pastor preaches (I can do it at services in the MPR-Baptist for gym).
So, when you add up reverent location with similar looking, smelling, and feeling it was not that large a leap for the Israelites to switch. Some of those coming to sacrifice may not have even realized the difference. It still looked like the tabernacle or temple, it still smelled the same, it felt the same, the priests were the same, what was that new statue on the way out again?
It is often easier to see the mistakes of others than it is to see our own. We rail against the Israelites while we read not realizing the ease with which something can be substituted until the original is no longer there. Subtle changes that taken in part are not much different but taken holistically have the opportunity to completely change the context of the subject matter. Perhaps we are too hard on the Israelites. Hundreds of years of slinging fat and blood against the altar they may not have realized how far off they were straying. Have we strayed in our religious practices, too? The answer is probably not what you first think, but if you honestly evaluate it, the beam in our eyes interferes with us seeing the Israelites' specks.