I heard a very good sermon yesterday about Abraham's willingness to sacrifice Issac to God. In order for anyone to be willing to sacrifice their child it would of course take great faith. It also would have taken great faith to sacrifice an animal. In modern day we often trivialize what an animal sacrifice truly must have meant. It went beyond a religious ritual, it was a sacrifice of a source of income or food. Any time a sacrifice was made the Israelites were saying, "Lord we trust you with our possessions and wealth."
Viewing things in this light really puts into perspective why God was so offended every time the Israelites sacrificed to false gods. They weren't merely carrying out a tradition that they had learned. I know I would never donate money to a cause that I didn't believe in. The Israelites wouldn't have either. They were saying with their livelihood that they trusted a false god to provide for them.
What we put our effort, time, and money into says loud and clear what gods we are worshipping. I know there are times when I certainly have to check myself. It's so easy to put children, family, or wants in front of God. Sacrifice however requires faith and that is something everyone can always stand to work on.