“You shall not make for yourself an idol ... You shall not bow down to them or worship them; for I, the Lord your God, am a jealous God, punishing the children for the sin of the fathers to the third and fourth generation of those who hate me, but showing love to a thousand generations of those who love me and keep my commandments."
Although idolatry is one of the worst offenses to God because he will not share his glory with another (Is 42:8), what is interesting about this commandment is God's jealousy. He has chosen us for his own not so that we can give his praise over to lifeless statues. As a husband is jealous for his wife, and will not share her with another, so also is the Lord jealous for us.
At first glance, God seems mean and vengeful, punishing children for the mistakes of their fathers to the third and fourth generation. It seems excessive and cruel until you realize the extent of his love. He shows love to a thousand generations of those who love him and keep his commandments. Compare three and four generations to a thousand and you will see the abundance of God's mercy. His love goes a lot farther than his justice. For just one person who loves the LORD and obeys all he commands, God will love and bless his children to the thousandth generation!
That one person is Christ and we rejoice in Him.