The simplest, purest truth of Catholicism is that, either, you pave the Way of Christ for others, or you're an obstacle.
Discipleship is the struggle to choose for the former.
"Whoever denies that Jesus is the Christ.
Whoever denies the Father and the Son, this is the antichrist." 1 John 2:22-28
This does not mean that if you were raised in another faith, or you were an inhabitant of a not-yet-evangelized, remote, Pacific island, God considers you the devil. It means, rather, that you are so selfish and so full of avarice that you treat others with contempt no matter what. Therefore, you cannot have the Spirit of Jesus in you.
Furthermore, if this is true of you, you have rejected the Holy Spirit of God, choosing, rather, for the spirit of the father of lies.
"Sing to the LORD a new song,
for he has done wondrous deeds;
His right hand has won victory for him,
his holy arm." Psalm 98:1-4
The simplest, purest truth of Catholicism is that if you have the Spirit of the Living Jesus in you, you are a person of thanksgiving and praise. You are that Way, because you have been forgiven of sins far too great to escape through your own effort and ingenuity. For that, your life is not your own any more, but God's in Jesus, and His Spirit.
This inspires not only 'Alleluia,' but 'Abba, Father.'
“I baptize with water;
but there is one among you whom you do not recognize,
the one who is coming after me,
whose sandal strap I am not worthy to untie.” John 1:19-28
The simplest, purest truth of Catholicism is that we are not worthy through our own fallen nature--but through the grace of repentance, and in the Blood of Jesus, we are 'more than conquerors,' becoming sons and daughters of God. Because of this we are called to evangelize the good news, not of our own greatness, but of the Goodness, the Truth, and the Beauty of our lives, and the lives of every human person, in the Lord Jesus Christ.
If one were to shrink down Catholicism into one simple statement, 'Merciful Jesus' would be it.
What do you think? firstname.lastname@example.org