The gospel is an important message promising us eternal life and the Kingdom of Heaven. Since the core of the gospel is the Passover of the New Covenant, the church that preaches the gospel must have the truth of the Passover.
Despite change from the Old Testament times to the New Testament times, there are still laws that God’s people must keep. It is the New Covenant that Jesus established, which is the Law of Christ.
The early Church kept the truth of the New Covenant such as the Sabbath and the Passover that Jesus established. Today, the Church of God is the only church that has restored the truth of the early Church.