If God will build Jerusalem for the people and their comfort, they must inhabit it for him and his glory. The promises and privileges with which God's people are blessed, should engage us to join them, whatever it costs us.
When Zion is enlarged to make room for all God's Israel, it is the greatest madness for any of them to stay in Babylon. The captivity of a sinful state is by no means to be continued in, though a man may be easy in worldly matters.
Escape for thy life, look not behind thee. Christ has proclaimed that deliverance to the captives, which he has himself wrought out, and it concerns every one to resolve that sin shall not have dominion over him.
Those who would be found among God's children, must save themselves from this world, see Ac 2:40. What Christ will do for his church, shall be an evident proof of God's care and affection. He that touches you, touches the apple of his eye.
This is a strong expression of God's love to his church. He takes what is done against her as done against the tenderest part of the eye, to which the least touch is a great offence. Christ is sent to be the Protector of his church.