Enrolled in heaven
The book of Hebrews is critical to understanding the worship of the church under the new covenant. Hebrews 12 contrasts the worship of the church with Israel’s worship at Sinai:
For you have not come to what may be touched, a blazing fire and darkness and gloom and a tempest and the sound of a trumpet and a voice whose words made the hearers beg that no further messages be spoken to them. For they could not endure the order that was given, “If even a beast touches the mountain, it shall be stoned.” Indeed, so terrifying was the sight that Moses said, “I tremble with fear.” But you have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, and to innumerable angels in festal gathering, and to the assembly of the firstborn who are enrolled in heaven, and to God, the judge of all, and to the spirits of the righteous made perfect, and to Jesus, the mediator of a new covenant, and to the sprinkled blood that speaks a better word than the blood of Abel. (Hebrews 12:18-24 ESV)
From this we understand that the church stands in the presence of Jesus as we gather every Lord’s day. But more than that, we stand in the company of angels, and of the saints that have gone before us. So one of the ways that we can remind ourselves that we grieve with hope (1 Thess 4:13) for saints who have gone before us is that we stand shoulder to shoulder with them every week in the worship of our king. We are sent back into the field of battle without them, but we rejoin them at our weekly furlough-feast.
This is another reason that our worship can be without mourning or weeping (Neh. 8:9), since we are spiritually experiencing a foretaste of all things being made right.