God commanded his people to keep appointed festivals and assemblies in order to remember God's history of saving his people out of Egypt and calling them to his holy people. Remembering God's grace to Jesus and celebrating with his people is also critical to our identity as believers and renewing his grace in our lives.
Firstly, God commands them to keep the Sabbath holy. Worshiping God each Sabbath Day strengthens our faith and identity as God's people. God emphasizes not to do any work. Secondly, God commanded them to keep the Passover to remember how God saved them through the blood of the Passover Lamb. The Festival of Unleavened Bread was to remember how they left Egypt hastily the next day with no time to put yeast in their dough. For 7 days, they should meditate on God's grace: how they plundered Egypt and crossed over the Red Sea as on dry ground. This looked forward to Jesus the true Passover Lamb. Thirdly, they should celebrate the Offering of the Firstfruits. It was a sign of thanksgiving to God and prayer for his blessing. It foreshadowed Jesus' resurrection. Fourthly, the Festival of Trumpets (Rosh Hashanah or the Jewish New Year) was to thank God for the entire harvest. It also looks forward to the harvest of souls for eternity.
Application: Father, help us to commemorate Jesus' grace of saving us by keeping holy assemblies.
One Word: Keep dedicated times of worship