What shall we do then? - The preaching of the Baptist had been accompanied with an uncommon effusion of that Spirit which convinces of sin, righteousness, and judgment. The people who heard him now earnestly begin to inquire what they must do to be saved? They are conscious that they are exposed to the judgments of the Lord, and they wish to escape from the coming wrath.

What.

Luke 3:8 Bring forth therefore fruits worthy of repentance, and begin not to say within yourselves, We have Abraham to our father...

Acts 2:37 Now when they heard this, they were pricked in their heart, and said to Peter and to the rest of the apostles, Men and brothers...

Acts 9:6 And he trembling and astonished said, Lord, what will you have me to do? And the Lord said to him, Arise, and go into the city...

Acts 16:30 And brought them out, and said, Sirs, what must I do to be saved?

John's Rebuke of Herod.
Preached May 15, 1853. JOHN'S REBUKE OF HEROD. "But Herod the tetrarch, being reproved by him for Herodias, his brother Philip's wife, and for all the evils which Herod had done, added yet this above all, that he shut up John in prison,"--Luke iii. 19, 20. The life of John the Baptist divides itself into three distinct periods. Of the first we are told almost nothing, but we may conjecture much. We are told that he was in the deserts till his showing unto Israel. It was a period probably, in which, …
Frederick W. Robertson—Sermons Preached at Brighton

A New Age and New Standards
As the Kingdom Comes Ethical Standards Must Advance Every approximation to the Reign of God in humanity demands an advance in the social relations of men, that is, an advance in ethics. Every really epochal advance must have it or slip back. There must be, first, better obedience to the moral principles already recognized and accepted by society; second, an expansion of the sway of ethical duty to new fields and wider groups of humanity; and third, a recognition of new duties and the assimilation …
Walter Rauschenbusch—The Social Principles of Jesus

Luke.
Lucas, Evangelii el medicinae munera pandens; Artibus hinc, illinc religione, valet: Utilis ille labor, per quem vixere tot aegri; Utilior, per quem tot didicere mori!" Critical and Biographical Schleiermacher: Ueber die Schriften des Lukas. Berlin, 1817. Reprinted in the second vol. of his Sämmtliche Werke, Berlin, 1836 (pp. 1-220). Translated by Bishop Thirlwall, London, 1825. James Smith (of Jordanhill, d. 1867): Dissertation on the Life and Writings of St. Luke, prefixed to his Voyage and …
Philip Schaff—History of the Christian Church, Volume I