The Jewish people are the people of God. In the Old Testament they were the nation of Israel, circumcised in the flesh, and in the New Testament they are true Israel (Romans 2), circumcised in the heart. Slightly controversial statement; Christians could refer to themselves as true Jews.
This is important because, as God’s nature doesn’t change, His affections toward His Old Testament saints can be the same affections toward His people now. Zechariah here is speaking the very words of God to Israel. God says to His people, “Those nations who attack you are attacking the pupil of my eye.”
When we hurt, God hurts.
Paul wasn’t persecuting Jesus… he was persecuting the Church. In actuality, Paul was persecuting the pupil of Jesus’ eye. Jesus took it that personally. He hurt.
Jesus wants to hurt with us. Not only that, but He commands us to cast our hurts onto Him so that we don’t have to carry them. Have you heard of a god like that?
Who is the attacker?
Satan, demons, the world, and… you. A lot of people freak out over Satan and demons. Not me. I very rarely think about them. I’m more concerned with the world (in its general darkness and love of sin) and I’m even more concerned with myself, in how I react to the world. I’m my worst enemy; I’m my worst attacker.
But God doesn’t hold my stupidity against me. Would a father say to his clumsy baby, “Pick yourself up,” when the child falls down? No, because the two are family.
By God’s grace, and through our faith, we are part of God’s family. We never need worry about our relationship with Him; we need to live by faith in the grace of God. A God who loves so much in spite of how much it hurts.