And if those days had not been shortened, no human being would be saved; but for the sake of the elect those days will be shortened. Then if any one says to you, 'Lo, here is the Christ!' or 'There he is!' do not believe it. For false Christs and false prophets will arise and show great signs and wonders, so as to lead astray, if possible, even the elect. Lo, I have told you beforehand. So, if they say to you, 'Lo, he is in the wilderness,' do not go out; if they say, 'Lo, he is in the inner rooms,' do not believe it. For as the lightning comes from the east and shines as far as the west, so will be the coming of the Son of man. Matthew 24:22–27 (RSV)
We are reminded throughout Advent that we are not merely preparing to celebrate Jesus' birth. If we are attentive to the lessons of Advent, they speak of His coming again as glorious Lord of all. Remember, Christmas is meaningless without Good Friday, Easter, and our Lord's promise to come again.
Jesus warns us that in the last days, many will seek to confuse or deceive believers. Some will do so because they are incompetent, caught up in the latest social movement popular in some circles of the Church, or wish to be well-liked, even popular among believers.
Others will come to deceive and destroy believers intentionally. These will do so because they hate God, wishing to wound Him by destroying the faithful. Others have fallen into the false belief that they are the latest prophet of God with a 'new word' to proclaim. The most wicked of all will think of themselves as a new messiah or replacement for Jesus.
How can a believer protect themselves from false witnesses and deceivers? The first way is to continue to trust Jesus in His Word. It is evident in Scripture that when He returns, there will be no doubt as to who He is. There will be nothing hidden of His divine majesty nor secret wisdom which must be discovered. As St. Paul writes of that day: "that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father." Philippians 2:10–11 (RSV)
Until that hour dawns upon us, all we need is the rightly proclaimed Gospel and the Holy Sacraments administered according to the Gospel. Christ has instituted and commanded that we proclaim the Gospel in this way. A Christian requires nothing other than these to remain faithful in Christ.
May Advent prepare your heart for the celebration of the Nativity of our Lord and His glorious return as Lord of all.