The following is revised from a previous version.
In light of Christ’s confession that he is the Good Shepherd, and the focus in the sermon on the shepherd metaphor, let’s consider the “good” part in this reflection. That said, the focus of this reflection is to think about what exactly goodness is in relation to God.
Herman Bavinck begins his discussion of goodness as an attribute of God by saying, “Among God’s ethical attributes first place is due to God’s goodness.” This is so because God’s goodness is associated with his perfections. When we think about what is good, e.g. love, we only find the perfect form of this quality in God. Whatever is good in God’s creation has come from God’s perfect goodness. Thus, God’s goodness is owed first place among God’s ethical attributes because it is through his goodness that we understand his love, wisdom, power, justice, and so on.
So, what does God’s goodness look like in his creation? In the Sermon on the Mount, Jesus describes the goodness of God as a general blessing of his love irrespective of the state of humanity. He says, “[God] he makes his sun rise on the evil and on the good, and sends rain on the just and on the unjust” (Matt 5:45). Paul echoed Jesus’ words about the general quality of God’s goodness during his first missionary journey. Speaking to the people of Lystra, he said, “In past generations [God] allowed all the nations to walk in their own ways. Yet he did not leave himself without witness, for he did good by giving you rains from heaven and fruitful seasons, satisfying your hearts with food and gladness” (Acts 14:16-17). That is to say, God’s goodness is not constrained to his own people. Out of the overflow of his perfect goodness, all of creation is blessed.
Paul’s words to the people of Lystra bring out a second aspect of God’s goodness. Out of his abundant goodness, God shows forbearance towards those who are alienated from him. Specifically, his goodness is evident in his patience. Peter picks up on this idea in his second letter where he says, “The Lord is not slow to fulfill his promise as some count slowness, but is patient toward you, not wishing that any should perish, but that all should reach repentance” (2 Pet 3:9). Indeed, God showed his patience toward the nations by giving them 400 years before he sent Israel into Canaan as his instrument of judgment against them (Gen 15:16). More broadly, God’s goodness by way of his forbearance is seen in his covenant with Noah, in which he promised not to destroy the earth by flood again. Instead, God promised to maintain seasons and cycles for as long as the earth remains (Gen 8:20-9:17). This is God’s goodness via forbearance writ large. The world has continued to exist in stability and order so that all might have opportunity to turn from idols to serve the living God.
But God’s forbearance as seen in his covenant with Noah reminds us of another aspect of God’s goodness, namely God’s goodness shown to those in misery. Recall that, even as God promises to preserve the world, he acknowledges that persistent and inherent sinfulness of man after the flood. Sin continues after the flood, and man continues to corrupt this world. So, oppression and pain and death also continue. But God shows his goodness through his mercy toward those in misery. Our Lord had compassion, i.e. mercy, on the crowds that had followed him into the wilderness to hear his teaching, and so he feeds them in an act of mercy (Mark 6:30-44). The Lord is merciful when he does not completely consume rebellious people in righteous judgment (Lam 3:22-23).
This last act of mercy is known by another name, grace. Bavinck says, “God’s goodness is much more glorious when it is shown to those who only deserve evil. It then bears the name of grace.” God’s goodness in his grace toward sinners is seen most clearly in the offering up of his only Son for our salvation. God’s grace is the height of his goodness because it displays the depths of his love. Indeed, “grace is central to the divine glory revealed in Jesus Christ (John 1:14), for all of salvation aims ‘to the praise of the glory of his grace’ (Eph 1:6). Therefore, God’s grace in Christ should be a keynote of our praise and worship to God.”
 Herman Bavinck, Reformed Dogmatics, ed. John Bolt, trans. John Vriend, 4 vols. (Grand Rapids: Baker Academic, 2003), 1:210.  Bavinck, Reformed Dogmatics, 1:214.  Joel R. Beeke and Paul M. Smalley, Reformed Systematic Theology (Wheaton, Illinois: Crossway, 2019), 1:787.