If we have learned anything in the past decade (or longer if we really have been paying attention), it is that breakdowns in relationships are really easy to do. Carefully curated articles and internet memes and "discussions" online and in person shared widely have the potential to drive deep wedges between people. Disputes over family matters become huge canyons that cannot be bridged. Professional differences lead to life long enmities.
All that pales in comparison to the rupture in humanity's relationship with God.
The first rupture was so long ago that we have collections and myths trying to explain how it happened. In many traditions it was the gods' jealousy of humanity, but in the Judaeo-Christian tradition, it was humanity which initiated the breach by going their own way, by abandoning God, by saying, "We do not need you to know what is true and life-giving and important." As a result, one may argue (and has argued, repeatedly, over centuries) that due to this separation, humanity has exposed itself to a host of ills and misfortunes.
Our Lord Jesus came among us to reverse that. We are (hopefully) familiar with the parable of the Prodigal Son,[1] in which Our Lord tells the tale of the son of a prominent man asks for an advance on his inheritance, and to our surprise at least receives it, and then goes and squanders it. The point of the tale is not that the Prodigal Son alienates his family (although he does), or not that he squanders it all (that he definitely does), or that he ends up because of his sin totally bereft and alone and perishing (but that point is there too). The point is that the Prodigal Son comes to the realization of his dire condition, comes back to his father to seek some small crumb of mercy for his repentance, and is surprised by the generous reconciliation and restoration with his father. The point here is that Jesus is stressing that for those who come to the realization that our condition is hopeless and turn to God for some small crumb of mercy, we find a stunning and surprising forgiveness and reconciliation with God completely out of proportion with the gravity of our situation.
In our psalm at Mass we sing, "Happy are they whose transgressions are forgiven, / and whose sin is put away!"[2] We each have shared in our ancestral sin of "going it alone" and departing from the protection of God and separating ourselves from the ultimate source of eternal life. In the psalm, however, we sing how if we simply put off our stubbornness, God's mercy puts us in a truly blessed relationship with Him where once there had been nothing. St. Paul tells us in the Epistle reading[3] that Jesus Our Lord has brokered that reconciliation for us, that because of His work, we are now reconciled with God, that our departure from God's overshadowing grace is now "water under the bridge. Because of this reconciliation, everything is new. We have a fresh start. We have because of Jesus Christ a new beginning where the old separation no longer has any meaning, where our sins are behind us and God wants to have a relationship with us and to give us participation in his fulness, in life without end or diminishment.
To that end, those of us who have come to know Jesus and His reconciling work are now tasked with bringing that news of reconciliation with God to those who have not heard. How do we do that? We have the example of Our Lord before us, not only telling of God's mercy, but showing the effects of God's mercy, by feeding those who are hungry, by giving water to those who are thirsty, by clothing those who have nothing to cover themselves, by caring for the sick, looking out for the disadvantaged and powerless, and by providing them dignity at the end of their time on earth. We had once gone on our own, separating ourselves not only from God but from each other, isolated and immune to the condition of others beyond ourselves. In Jesus we find that isolation reversed, and now reconciliation with God and by extension with everyone else we have excluded. We can be joyful at this time, because we were lost to God, but he found us. We were dead to Him, but now we are alive.
[2] Ps. 32.1
[3] 2 Cor. 5.16-21