What is the doctrine of regeneration?
4 But when the goodness and loving kindness of God our Savior appeared, 5 he saved us, not because of works done by us in righteousness, but according to his own mercy, by the washing of regeneration and renewal of the Holy Spirit,
17 So faith comes from hearing, and hearing through the word of Christ.
The doctrine of regeneration is the truth taught in Scriptures like John 3:3, 6-8, Titus 3:4-5, Ephesians 2:1-7, etc., concerning the work of God the Holy Spirit to bring the beloved chosen of God to spiritual life out of their spiritually-dead state that all mankind shares in Adam. This work of regeneration precedes conversion and results in faith alone by Christ alone for salvation (Ephesians 2:8-10). God brings about all this through the means of the Gospel preached and shared (Romans 10:17).
R.C. Sproul stated about regeneration and conversion:
“Regeneration is the work of God the Holy Spirit as He supernaturally and immediately changes the disposition of the soul from spiritual death to spiritual life.
Conversion is a result of regeneration. When we are converted, we’re turned around and we move in a different direction.”
Being born of the Holy Spirit precedes faith for faith is a gift of God. Are you born again? Are you trusting in the Lord Jesus?
 Sproul, R.C. What’s the difference between regeneration and conversion? (ligonier.org). https://www.ligonier.org/learn/qas/difference-between-regeneration-and-conversion. Accessed on 9/21/2021.