In the first reading from Revelation, we read: "I, John, saw another angel come up from the East, holding the seal of the living God. He cried out in a loud voice to the four angels who were given power to damage the land and the sea, "Do not damage the land or the sea or the trees until we put the seal on the foreheads of the servants of our God.""
In the ancient world, a seal represented the person whose seal it was and his authority. In the gospel of John, we read that the Father has set his seal on Christ. He has been consecrated as Son of God (Jn 10, 36). As such, he has authority over everything in the cosmos; for the divine seal represents his power over all creatures and over history. In him we are marked with the seal of the living God; all those so marked belong to Him and share in the divine nature. That seal is the mark of the servants of God, and it is our safeguard during the time of the ultimate testing; it is our protection, as the first reading makes clear. And that is why we need not be afraid. As the Psalm says: "You shall not fear the terror of the night nor the arrow that flies by day, nor the pestilence that roams in darkness, nor the plague that ravages at noon. Though a thousand fall at your side, ten thousand at your right hand, you it will never approach; his faithfulness is buckler and shield" (Ps 91, 7). Christ came to deliver us from the fear of death, as we read in the Letter to the Hebrews: "... that through death he might destroy the one who has the power of death, that is, the devil, and free those who through fear of death had been subject to slavery all their life" (Heb 2, 15).
From the first reading, we also learn that salvation comes not from our own efforts, but from God and from the Lamb . We cannot save ourselves. The Lamb of God is savior. He is not merely a role model for us, someone we choose to emulate - there are countless role models for us to emulate. In fact, that's what the saints are. Christ, on the contrary, makes saints. He is the cause, the fount of all holiness. He brings salvation in the here and now; he makes us a new creation. We are not born in a state of grace; we are born spiritually dead, which is why we need to be washed clean in the waters of baptism, which is an entering into the tomb of Christ, into the Passover (Pasch) of the Lamb.
Furthermore, the first reading points out that this multitude in white robes are the ones who have lived through the time of the great tribulation, not a time of great peace. They have washed their robes and made them white in the Blood of the Lamb. The world is at war, and Christ is at the center of that war, that is, the reason for it. He is the perpetual sign of contradiction. That's what Simeon said to Mary when he beheld the child Jesus: "This child is destined to be the downfall and the rise of many in Israel, a sign that will be opposed (Lk 2, 34). And so, Christians are not dreamers. We don't dream of a day when the world will be at peace as a result of our own efforts. On the contrary, we hope for the Second Coming of Christ, the Parousia, when Christ will bring about a new heaven and a new earth: "Then I saw a new heaven and a new earth. The former heaven and the former earth had passed away, and the sea was no more. I also saw the holy city, a new Jerusalem, coming down out of heaven from God, prepared as a bride adorned for her husband. ...He will wipe every tear from their eyes, and there shall be no more death or mourning, wailing or pain, for the old order has passed away" (Rev 21, 1-2).
Christ makes all things new, not us. Peace on earth outside of Christ's Second Coming is impossible. If we could bring about peace on earth through our own efforts, then Christ lied when he said: "If the world hates you, know that it has hated me before it hated you. If you were of the world, the world would love its own; but because you are not of the world, but I chose you out of the world, therefore the world hates you." (Jn 15, 18).
The world will always hate those marked with the seal of the living God. The reason is that those who belong to Christ are radically different; the fundamental orientation of their lives is different, their thinking is different because their hearts are different, and the Beatitudes in today's gospel are the basic contours of the heart of one who is a new creation in Christ, marked with his seal. They are poor in spirit, which means they know their utter need for God; those not marked with the seal of the living God are oblivious to that radical need. Those marked with the seal of the living God mourn, for they are not at home in this world, which is characterized by sin and opposition to Christ, and it is this sin and opposition to him that is a constant source of sorrow for them. It does not mean they cannot rejoice - they rejoice in the hope of Christ's victory, not in the delights and false promises of this world; they are meek, slow to anger like Christ, the Lamb of God, unlike those who are of this world, quick to dismiss and seek the ruin all those who are not part of the world's ever changing and current "group think"; they hunger and thirst for what is right, with the hunger and thirst of a first century Palestinian under desert heat, unlike those who are less concerned for what is truly right and good than they are for revenues; they are merciful, because they know mercy has been shown to them in the forgiveness of their own sins, unlike the world, which is relentless in the pursuit of the destruction of those who are not of the same mind; they are pure of heart, undivided in their love for God, unlike the world that has made itself its own god; they are peacemakers, because they love all who belong to God, unlike the world, that aborts or euthanizes inconvenient life and that is at perpetual war, a lucrative racket; and finally they are persecuted on account of Christ; they are not tolerated by the world, and any Christian who is loved by the world is probably a Christian in name and appearance only. For all its talk of tolerance, the one thing the world will not tolerate is anyone who stands for Christ and proclaims him as savior of mankind and Lord over all.
There is a price to pay for befriending the world, and that price is a loss of power in the proclamation of Christ, and a serious weakening of our ability to move others to conversion. Christians who try to befriend the world inevitably reduce Christ to suit the world's taste, to something the world can live with, a Christ that is not the Lord of this world, but one subservient to it. The Church is not a means to world peace, but the means of salvation, the sacrament of Christ's kingdom. What drives us is not optimism, but the theological virtue of hope in him. Christ is Lord of history, and our task is to allow ourselves to be transformed in him and to be used by him according to his plan in the bringing about of his kingdom, the day and the hour of which only the Father knows (Mt 24, 36).