Jesus tells Peter as recorded in Matthew 16:18, “ I also say to you that you are Peter, and upon this rock I will build My church; and the gates of Hades will not overpower it.”
This rock was Peter’s confession recored in verse 16 “You are the Christ, the Son of the living God.”
That Jesus is the Christ, the Son of the living God is the unassailable truth that can not be overcome. There is no power on earth or heaven that can triumph over this truth and the person of the Lord Jesus Christ.
Thus the church is triumphant on the earth and should press forward with this belief that Jesus is the Christ and that no power on earth or heaven can stop it or us if we preach this Gospel message.
The church is strongest when it preaches the Gospel that Jesus is the Christ and the He alone redeems sinners. The church is weak and can be defeated, at least temporarily, with all other messages.
Preach the Gospel as Paul says in II Timothy 4:2, “In season and out of season” (all the time). The church will grow and expand and cover the earth.