The Seal of God and the Mark of the Beast^{*1904, Testimonies for the Church 8:117 (Forgetfulness).}

In God's word we are shown the consequences of proclaiming the third angel's message. “The dragon was wroth with the woman, and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ.” Revelation 12:17. A refusal to obey the commandments of God, and a determination to cherish hatred against those who proclaim these commandments, leads to the most determined war on the part of the dragon, whose whole energies are brought to bear against the commandment-keeping people of God. “He causeth all, both small and great, rich and poor, free and bond, to receive a mark in their right hand, or in their foreheads: and that no man might buy or sell, save he that had the mark, or the name of the beast, or the number of his name.” Revelation 13:16, 17.3TT 232.1

The sign, or seal, of God is revealed in the observance of the seventh-day Sabbath, the Lord's memorial of creation. “The Lord spake unto Moses, saying, Speak thou also unto the children of Israel, saying, Verily My Sabbaths ye shall keep: for it is a sign between Me and you throughout your generations; that ye may know that I am the Lord that doth sanctify you.” Exodus 31:12, 13. Here the Sabbath is clearly designated as a sign between God and His people.3TT 232.2

The mark of the beast is the opposite of this—the observance of the first day of the week. This mark distinguishes those who acknowledge the supremacy of the papal authority from those who acknowledge the authority of God.3TT 232.3