Centrality of Preaching

I was reading an article in my Kittels and I went on a side trip on the centrality of preaching (κήρυγμα) in the building of God's kingdom. Here are some key verses on preaching.

Matthew 4:17
From that time Jesus began to preach, saying, “Repent, for the kingdom of heaven is at hand.”

Romans 10:14
How then will they call on him in whom they have not believed? And how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching?

Romans 16:25-27
Now to him who is able to strengthen you according to my gospel and the preaching of Jesus Christ, according to the revelation of the mystery that was kept secret for long ages but has now been disclosed and through the prophetic writings has been made known to all nations, according to the command of the eternal God, to bring about the obedience of faith—to the only wise God be glory forevermore through Jesus Christ! Amen.

1st Corinthians 2:4 KJV
And my speech and my preaching was not with enticing words of man's wisdom, but in demonstration of the Spirit and of power:

1 Corinthians 9:16-18
For if I preach the gospel, that gives me no ground for boasting. For necessity is laid upon me. Woe to me if I do not preach the gospel! For if I do this of my own will, I have a reward, but if not of my own will, I am still entrusted with a stewardship. What then is my reward? That in my preaching I may present the gospel free of charge, so as not to make full use of my right in the gospel.

1 Timothy 2:7
For this I was appointed a preacher and an apostle (I am telling the truth, I am not lying), a teacher of the Gentiles in faith and truth.

2 Timothy 4:2-4
I charge you in the presence of God and of Christ Jesus, who is to judge the living and the dead, and by his appearing and his kingdom: preach the word; be ready in season and out of season; reprove, rebuke, and exhort, with complete patience and teaching. For the time is coming when people will not endure sound teaching, but having itching ears they will accumulate for themselves teachers to suit their own passions, and will turn away from listening to the truth and wander off into myths

Titus 1:1-3
Paul, a servant of God and an apostle of Jesus Christ, for the sake of the faith of God's elect and their knowledge of the truth, which accords with godliness, in hope of eternal life, which God, who never lies, promised before the ages began and at the proper time manifested in his word through the preaching with which I have been entrusted by the command of God our Savior;

2 Timothy 4:17
But the Lord stood by me and strengthened me, so that through me the message might be fully proclaimed and all the Gentiles might hear it. So I was rescued from the lion's mouth.

A comment from a theological dictionary on 2 Timothy 4:17
God has strengthened him so that even in hours of affliction and isolation he has fully discharged his office as a preacher. Before judges and listeners, before the whole court, he did not stand a a defendant but as a herald. Thus all nations heard the message through him. Representatives of peoples who knew nothing of Christ had the opportunity to hear his preaching. In this way he faithfully fulfilled his office. (p.717, kerygma, TDNT Vol. III)