And since we have the same spirit of faith in keeping with what is written, I believed, therefore I spoke, we also believe, and therefore speak.2 Corinthians 4:13 HCSB

Paul is quoting Psalms 116:10

I believed, even when I said, “I am severely afflicted.”
Psalms 116:10 HCSB
https://bible.com/bible/72/psa.116.10.HCSB

The things we believe are the things we talk about. If we believe that which is contrary to the Word of God then we are not speaking the truth.

Sanctify them by the truth; Your word is truth.
John 17:17 HCSB
https://bible.com/bible/72/jhn.17.17.HCSB

Therefore I am informing you that no one speaking by the Spirit of God says, “Jesus is cursed,” and no one can say, “Jesus is Lord,” except by the Holy Spirit.
1 Corinthians 12:3 HCSB
https://bible.com/bible/72/1co.12.3.HCSB

So faith comes from what is heard, and what is heard comes through the message about Christ.
Romans 10:17 HCSB
https://bible.com/bible/72/rom.10.17.HCSB

The trinity always works together. Jesus --the Word of God, the Holy Spirit --the spirit of God, and God -- the Father are always working in us to perfect us into the image of Jesus. When we are in alinement with the truth the Holy Spirit is speaking through us to win the souls around us to Jesus. but when we are not then we are speaking out of our own flesh and could be turning them away from Jesus.

Act wisely toward outsiders, making the most of the time.  Your speech should always be gracious, seasoned with salt, so that you may know how you should answer each person.
Colossians 4:5‭-‬6 HCSB
https://bible.com/bible/72/col.4.5-6.HCSB