What is the seal in the foreheads of God's end-time people? Rev. 7:1-3; Rev. 14:1.
The Greek of Revelation 14:1 translates: "having His name and His Father's name written upon their foreheads." (Compare Rev. 3:12; Rev. 22:4.) The Father's name and Christ's name are symbols of their character.
The psalmist wrote: "I will give to the Lord the thanks due to his righteousness, and I will sing praise to the name of the Lord. the Most High" (Ps. 7:17, RSV). The Lord's name is the symbol of His righteousness. When we praise the name of the Lord, we praise His holy character. The psalmist also wrote: "Ascribe to the Lord the glory of his name" (Ps. 29:2, RSV). The Lord's glory is His infinitely perfect character.
How does Christ give us His character? Eph. 1:13,14; Rev. 3:5; Rev. 6:11; Rev. 19:7, 8.
The Holy Spirit brings Christ's righteousness to the heart of every true Christian (Rom. 8:9, 10). Enjoying the new-birth experience (John 3:1-16), we have the initial seal of the Spirit, the "guarantee of our inheritance until we acquire possession of it" (Eph. 1:14, RSV).
The presence of the Spirit in our hearts enables spiritual growth toward complete victory over sin, which is the prerequisite to reception of God's end-time seal. Those whose names are retained in the book of life are overcomers through Christ's power (Rev. 3:5). Revelation 6:11 translates literally: "And there was given to each of them [the righteous dead] a white robe, and it was said to them that they should rest a little longer, until their fellow servants and their brethren, who are about to be killed as they were, might be made complete." By the power of the Holy Spirit, God's end-time people are made completely victorious in Christ during the "marriage of the Lamb," the pre-advent judgement (Rev. 19:2, 7, 8). Then they are sealed in their foreheads. Their names are eternally retained in the book of life, and Satan has no more power over them. (See Early Writings, pp. 270, 271.)
God's name, His character, is revealed by His creative and redemptive work, of which the Sabbath is the sign (Exod. 20:8-11; Exod. 31:13). Those who receive the bestowal of Christ's character by the gift of the Holy Spirit observe the seventh-day Sabbath as the great memorial of, and aid to, their spiritual victory in Christ.