Ephes. 2:14-22 (ESV)
For he himself is our peace, who has made us both one and has broken down in his flesh the dividing wall of hostility  by abolishing the law of commandments and ordinances, that he might create in himself one new man in place of the two, so making peace,  and might reconcile us both to God in one body through the cross, thereby killing the hostility.  And he came and preached peace to you who were far off and peace to those who were near.  For through him we both have access in one Spirit to the Father.  So then you are no longer strangers and aliens, but you are fellow citizens with the saints and members of the household of God,  built on the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone,  in whom the whole structure, being joined together, grows into a holy temple in the Lord.  In him you also are being built together into a dwelling place for God by the Spirit.
For He himself is our peace. He is the peace of God that surpasses all understanding. For He has broken down the dividing wall of hostility in His flesh, the very flesh He gives to us. That is because in His flesh dwell both divine and human natures together in peace and harmony as they once dwelt in the garden of Eden. Jesus is both God and man. Fully God and fully man, light of light very God of very God, being of one substance with the Father. Yet Jesus is also very man of very man, born of a virgin, only without sin. In His flesh Ge reconciled man and God, by dying on behalf of man. He created in Himself one new man in the place of two. That is now we are now part of that one new man. We are the body of Christ. He is our head. So He made peace reconciling us both to God in one body through the cross thereby killing hostility. He reconciled us through the cross in his body, that he now incorporates us into. So now we are no longer strangers but citizens of the household of God, built on the foundation of the apostles and prophets, Christ being the cornerstone.
The household of God has a foundation built on the apostles and the prophets. This is what it means to be an apostolic Church, a church that builds on the foundation of the apostles and prophets. That means we bring people into the household of God by preaching Christ and him crucified, the teaching of the apostles and prophets. The cornerstone of the apostolic doctrine, the focus of the prophets is Christ crucified. Without the cross there is no gospel. Without the cross the prophets have no focus. The Cross brings all the doctrines, all the articles of faith, all the dogmas of the church and unifies them. Christ is at the center of it all. If it does not serve to proclaim Christ, to show Christ, to preach the cross then it is useless, it is nothing. All dogma, all doctrine, all teachings of the church, all the articles of faith must pass through the Cross.
So, it is not like if you preach the cross Sunday after Sunday you neglect the other teachings of the Church, the other articles of faith. But in preaching the cross you preach these other articles, and give them focus, give them their true meaning and purpose. Seriously, a book that writes three hundred pages about the Trinity, but fails to relate it to what happens in Christ on the Cross is a useless book. The Trinity is not the gospel. But neither is the gospel, the death of God made man on the cross, made possible without the Trinity. This is why when we confess the Trinitarian faith of the Apostles, the teaching of the apostles in the Nicene Creed, we find justification, salvation, at the center: “Who for us men and for our SALVATION came down from heaven, and was incarnate by the Holy Spirit of the Virgin Mary and was made man, and was crucified also for us under Pontious Pilate.” He did it for us, FOR YOU, so you can say “for me,’ and together as one body we can say for us.