God commands His people to rejoice during the Feast of Tabernacles, as stated in Deuteronomy 16:13-15, where they are instructed to observe the seven-day feast with their families, servants, Levites, strangers, the fatherless, and widows, because He will bless them in their produce and in all the works of their hands. This rejoicing occurs at the place He chooses and stands alongside the requirement to learn to fear Him, a term that encompasses both reverential awe and the possibility of terror. The command demonstrates that rejoicing does not arise automatically but requires deliberate choice, just as keeping the Sabbath requires choice. Rejoicing connects directly to the spiritual meaning of the Feast as a celebration of the coming Millennium, the environment in which the great fall harvest will occur amid peace, harmony, abundance, and faithfulness. Yet the Millennium will also contain monumental problems that demand changed hearts. God will restore devastated lands to greater productivity than before, but only after He sprinkles clean water on His people, removes their heart of stone, and places His Spirit within them so they walk in His statutes. The same principle applies at the Feast: participants bring their own character, attitudes, and problems, and unity and rejoicing will result only when they yield to the Spirit, exercise wisdom from above that is pure, peaceable, gentle, and full of mercy and good fruits, and sow the fruit of righteousness in peace. Rejoicing is further linked to sacrifice. In Deuteronomy 12, instructions for keeping the feasts require bringing tithes and offerings to the chosen place and rejoicing before the Lord. Although animal sacrifices have ended, spiritual sacrifices continue through giving time, service, praise, and consideration for others. These acts imitate the outgoing concern that defines God and produce the peace and harmony that allow rejoicing to flourish. When people choose instead to follow human nature through anger, resentment, or offense, their focus shifts away from producing the fruits of righteousness, hindering both personal rejoicing and the Feast's success. Thus rejoicing depends on the daily decision to yield to God's Spirit, make peace, and serve others, the same choices that will fill the Millennium with the beauty and abundance God has promised.

God rejoices both when blessing His people and when bringing painful judgments upon the guilty, finding satisfaction in doing what is right regardless of outward circumstances or the absence of happy exuberance. This understanding of rejoicing extends beyond momentary feelings of gladness to a deliberate sense of fulfillment in fulfilling divine purpose. The same principle applies to the commanded rejoicing during the Feast of Tabernacles, which God requires His people to observe with offerings, holy convocations, and active participation rather than passive attendance. Rejoicing is not confined to prosperous or problem-free conditions but must be chosen and produced even amid trials, irritants, or spiritual challenges that precede or occur during the Feast. Scripture links rejoicing directly to sacrifice, as seen in the requirement to bring offerings and to share the fruits of one's labor—both physical and spiritual—with family, servants, Levites, strangers, orphans, and widows. These spiritual fruits, drawn from the Spirit's produce of love, joy, peace, longsuffering, kindness, goodness, faithfulness, gentleness, and self-control, are to be carried to the Feast and deliberately shared through service, generosity, and outgoing concern. Such sharing fulfills the command to rejoice and mirrors God's own pattern of giving. The Feast therefore serves as the optimal setting for practicing these attributes, enabling participants to imitate God by prioritizing His Kingdom, bearing one another's burdens, and avoiding self-centered pursuits that leave one spiritually empty. In this way rejoicing becomes an active expression of love that connects personal conduct throughout the year to the Feast's purpose of spiritual growth and preparation for the future.

God's insistence that His people rejoice constitutes the third element of His instructions for the Feast of Tabernacles. This rejoicing must center on His faithfulness rather than serve as an occasion for mere pleasure or self-centered merriment. The joy is intended to produce more than an elevated mood; it should foster recognition of all that God has accomplished throughout the year and reinforce a proper fear of Him. Ancient Israel demonstrated the danger of rejoicing with the wrong focus. Although the people offered sacrifices and made a joyful noise as commanded, God rejected their observances because idolatry, injustice, and unrighteousness persisted among them. Their burnt offerings falsely implied wholehearted devotion to Him, their meal offerings falsely implied dedication to others, and their peace offerings falsely implied genuine fellowship, all while they worshipped Molech and neglected true righteousness. The absence of any reference to the drink offering or the sin offering further revealed their condition: they showed no interest in expending themselves in service to others and no awareness of their own sin or need for forgiveness. Consequently, they departed the Feast unchanged, returning to the same idolatry and unrighteousness. Their celebration lacked the fear of God that would have produced hatred of evil and genuine transformation. This failure underscores the connection between rejoicing and the fourth element of the instructions, the fear of God. Because God is consistently faithful, both in bestowing blessings and in executing judgment, those who rejoice in His faithfulness grow in reverence for Him. The Feast therefore functions as a celebration of that faithfulness, enabling participants to learn to fear God always.