Armstrongism explicitly rejects Christmas, Easter, Halloween, and birthday celebrations as pagan practices without biblical warrant. These are seen as corruptions introduced into Christianity through syncretism with pagan religions. Instead, Armstrongism emphasizes the biblical festivals given by God to Israel: Passover, Days of Unleavened Bread, Pentecost, Feast of Trumpets, Day of Atonement, Feast of Tabernacles, and the Last Great Day.

These annual observances are presented as the true Christian calendar, prefiguring aspects of God's plan of salvation and the Millennium. Believers are called to separate from worldly holiday traditions and to observe God's divinely appointed feasts. This critique of pagan-derived holidays is one of Armstrongism's most distinctive practices and reflects its broader restorationist conviction that the early apostolic church observed these biblical feasts.