We will win because Christ crucified has risen in victory to God's right hand and he has poured out his Holy Spirit on mankind. As St Peter said at Pentecost:
Now raised to the heights by God's right hand, he has received from the Father the Holy Spirit who has been promised and what you see and hear is the outpouring of that Spirit. For David ... said "The Lord declared to my Lord, take your seat at my right hand, till I have made your enemy your footstool". [Acts 2:33-35]
There are three considerations:
Jesus sits victorious at God's right hand.
His enemies are in the process of being wiped out (made into his 'footstool').
The outpouring of the Spirit gives the Church a share in the victory.
John 16:7-11 describes the Spirit's work as convicting the world of its sin, of showing that Jesus was in the right by his ascending to the Father and by the prince of this world being already condemned.
As the Catechism puts it, 'The Holy Spirit causes the world to enter into the "last days," the time of the Church, the Kingdom already inherited though not yet consummated.' (CCC 732)
To stay in the fight and end up on the winning side we need to focus on Jesus, who is at the right hand of the Father, as the Letter to the Hebrews encourages us:
Let us fix our eyes on Jesus, the author and perfecter of our faith, who for the joy set before him endured the cross, scorning its shame, and sat down at the right hand of the throne of God. [Hebrews 12:2]
To describe his part in this fight, Jesus called himself "Son of Man." This was a reference to a character in a vision that the Prophet Daniel had of a 'son of man' 'coming on the clouds of heaven' and on whom was conferred a 'kingship that will never end'. [See Daniel 7:13-14]
The return of the Jesus in glory was the end-game of the first Christians. They had either seen Jesus in his risen body and/or been convinced by the Holy Spirit of his presence at the right hand of the Father. Like Jesus, they also fought to win humanity to God before the consummation of the world. The New Testament teems with references to Jesus' return in glory.
The attachments below have a lot of scriptural references to encourage us in the fight. And we can have as our goal the Church bringing the whole of Humanity home to God because 'the Lord wants nobody to be lost and everybody to be brought to repentance'. [2 Peter 3:9]