John 3:18 He who believes into Him is not condemned; but he who does not believe has been condemned already, because he has not believed into the name of the only begotten Son of God. 36 He who believes into the Son has eternal life; but he who disobeys the Son shall not see life, but the wrath of God abides upon him.
To believe is the only way for us to receive salvation and regeneration. It is absolutely a matter of faith. Regardless of how much we can work or how good our work may be, we cannot be saved and regenerated by our work. Our work does not count in this matter. Only faith counts. Salvation and regeneration must be by faith. It is by faith in the Lord, by believing in the Lord, that we receive the forgiveness, the release from God's condemnation negatively. It is also by faith, by believing in the Lord, that we receive eternal life, the divine life of God, positively for our regeneration.
To believe in the Lord means to receive Him (John 1:12). The Lord is receivable. He is now the life-giving Spirit, with His complete redemption, waiting for and expecting us to receive Him. Our spirit is the receiving organ. We can receive the Lord's Spirit into our spirit by believing in Him. Once we believe in Him, He, as the Spirit, enters into our spirit... By believing in Him, we get into Him to be one with Him, to partake of Him, and to participate in all that He has accomplished for us.