The first reading and the gospel speak of humility and helping the poor; the second reading is about the community within which we worship.
The second reading — Hebrews 12:18-19, 22-24a — is the last of four selections from Hebrews 11 and 12 that were proclaimed on the 19 through the 22nd Sundays. (We also hear readings from Hebrews on Christmas, Good Friday, five Sundays in Year B, and 24 successive weekdays in odd-numbered years.) This passage contrasts God’s appearance at Mount Sinai, when he gave the Law, and the heavenly worship in which we participate in our liturgy. At Sinai God was unapproachable (except by Moses) and the manifestation of his presence was terrifying to the people. But now God has made himself approachable, and the assembly of angels and saints is joyful. We join this assembly through Jesus and the covenant ratified by the shedding of his blood, which is figuratively sprinkled on us when we receive it in holy Communion.
The first reading — Sirach 3:17-18, 20, 28-29 — begins with a recommendation similar to the advice Jesus seemingly gives in the gospel: humility will win you love. Next, though, it tells us that God favors those who are humble. One aspect of humility is knowing your limitations. Finally, there is a seemingly abrupt turn to a recommendation of almsgiving.
The responsorial psalm — verses taken from Psalm 68 — picks up the thought of the poor and needy: the beneficiaries of our almsgiving. God cares for them; his blessings on the land are for their good.
The gospel pericope — Luke 14:1, 7-14 — has two sections after the initial verse setting the scene: the advice to the guests, and the advice to the host. The advice to the guests, taken literally, seems strange coming from Jesus. But the message is not to be taken literally, however effective such a tactic might be in certain contexts. It becomes clearer when we realize, as St. Paul says in Philippians 2:5-11, that Jesus is the one who took the lowest place: laying aside divinity, becoming human, and accepting death by crucifixion. Then the host of the eternal banquet called him to the highest position. We, too, must not cling to our status; we must be willing to accept whatever cross comes our way for the sake of others. This is easy to say, but not at all easy to do.
The advice to the host furnishes a way for taking the advice given to the guests. As in the first reading, the advice is to give to the needy — which is truly giving because one doesn’t receive comparable value in return. This is what Jesus did when he humbled himself. He brought us all to the banquet with the Father, despite the fact that none of us has any way of repaying him. We are all recipients of God’s mercy and should try to show it to others. Humility includes realizing that we’re not inherently better than anybody else, and we don’t deserve to be better off than they are.