The most fearful threatening ever addressed to mortals is contained in the third angel's message. That must be a terrible sin which calls down the wrath of God unmingled with mercy. Men are not to be left in darkness concerning this important matter; the warning against this sin is to be given to the world before the visitation of God's judgments, that all may know why they are to be inflicted, and have opportunity to escape them. SR 383.2
In the issue of the great contest, two distinct, opposite classes are developed. One class “worship the beast and his image, and receive his mark,” and thus bring upon themselves the awful judgments threatened by the third angel. The other class, in marked contrast to the world, “keep the commandments of God, and the faith of Jesus.” Revelation 14:9, 12. SR 383.3
Such were the momentous truths that opened before those who received the third angel's message. As they reviewed their experience from the first proclamation of the second advent to the passing of the time in 1844, they saw their disappointment explained, and hope and joy again animated their hearts. Light from the sanctuary illuminated the past, the present, and the future, and they knew that God had led them by His unerring providence. Now with new courage and firmer faith, they joined in giving the warning of the third angel. Since 1844, in fulfillment of the prophecy of the third angel's message, the attention of the world has been called to the true Sabbath, and a constantly increasing number are returning to the observance of God's holy day. SR 383.4