How can God be jealous?
The jealousy of God is a difficult thing to understand because of the different meanings attached to the word. We often mistake jealousy for a negative emotion caused by a strong desire for something someone else has (such as their expensive clothes or car). The desire can also be for a characteristic that someone else possesses such as wishing we were as beautiful or wise as the other person. However this is not "jealousy" but "envy".
Whilst jealousy is a similar emotion it does not originate from desiring something we have never had. Instead Jealousy is experienced due to the loss of something which is highly valued by a person. Commonly jealousy comes from some loss within a close human relationship. For example we can understand that an ex-boyfriend might be jealous for his ex-girlfriend’s affection and would find it hard to see her affections transferred to another. But we can also understand the jealousy of a child when a new baby is born into the family. The child is jealous for the mother’s attention and affection.
Obviously it is not right to jealously attempt to control someone or attempt to take away their freedom. When humans are jealous over one another, it is often because of a desire for selfish gain and often it results in manipulation and unhappiness.
When it comes to God’s jealousy we know from the Bible that His jealousy relates to the relationship He has with His people. See for example Exodus 20:5 or Deuteronomy 4:24. What these passages teach about God’s character is that God is jealous for His people’s worship, adoration, devotion and obedience. In other words God longs for His people to be in good relationship with Him. When His people give the affection and devotion that God alone deserves to idols (anything that is not God) then He is personally hurt and rightly warns that He will punish His people for their idolatry.
For a New Testament continuation of this theme see 2 Corinthians 11:2 in which the apostle Paul explains that Godly jealousy relates to the purity of the relationship between God and His people. It is with our best in mind that God longs jealously over us. He desires that we will be purely devoted to Him in the same way a husband and wife are devoted to each other. After all we belong to Him, we were created for Him and when we come into a restored friendship with God through Christ we realise that our relationship with God is of the highest importance for us.
So God’s jealousy over us is not manipulative or negative but rather it is a sign of His love for us and His desire that we should be in right relationship with Him.