Modalism is a mistake because, in the name of preserving the simplest possible concept of God’s unity and defending the totality of God’s presence in the Incarnation, it subjects God to time and space.
With Amos, the modern Christian must believe and proclaim that a prosperous economy cannot be built on a unjust society, because the foundation of peace and prosperity can be only justice, and especially justice that is built upon the acknowledgement that God is God and we are not.
Even after the destruction of Samaria, Amos is depicting the Israelites as not only not returning to God but actively avoiding turning to God out of Genesis 3-like fear. Rather than turning to God, those with wicked and foolish hearts look at their sufferings, which they brought on themselves by their own wickedness and foolishness, and they blame God.
Whatever strength you feel you possess that you can boast in, God does not think much of it. God is not against your strengths and talents, but when you rely on them rather than on him to secure and defend your prosperity, God says that all your excellence, all that in which you would take pride, is nothing next to his power. Your mighty fortress will not secure you against his justice.