Leviticus 23:4, 37, 38 These are the feasts of the Lord, even holy convocations, which ye shall proclaim in their seasons…These are the feasts of the Lord, which ye shall proclaim to be holy convocations, to offer an offering made by fire unto the Lord, a burnt offering, and a meat offering, a sacrifice, and drink offerings, everything upon his day: Beside the sabbaths of the Lord, and beside your gifts, and beside all your vows, and beside all your free will offerings, which ye give unto the Lord.
The people of God were told to respond to God’s mercies by coming together in holy convocation three times a year, for the Feasts of Passover, Pentecost and Tabernacles. They were to proclaim these feasts. They announced, advertised, supported, set up, planned for, paid for, and then participated in these three celebrations every year at the tabernacle and then the temple. This was in addition to the weekly Sabbaths and daily offerings.
The Jews were faithful in proclaiming, holding, and attending these annual Feasts and weekly Sabbaths until the time of Jesus. The NT Church carried on this traditional response by proclaiming Christmas, Easter, and Pentecost. (Although Pentecost doesn’t get the commercial and secular support of the world, it really is still worthy of a Holiday.) The NT also carries through the tradition of the Sabbath by organizing Divine Service weekly on Sunday. We also continue daily family and private devotions.
All of this proclaiming involves gathering Christians, building churches for worship and celebration, giving generously for the supporting and maintaining of churches, volunteering time and talent, supplying means for fellowship, and sending missionaries throughout the world. A lot goes on in proclaiming. We respond to the Gospel by organizing worship. The Church becomes a focal point in our lives all in response to the Gospel.