Charles H. Spurgeon said, "You are born again if you believe that Jesus is the Christ, if you are relying upon a crucified Savior you are assuredly begotten again unto a lively hope."
We may not comprehend all the movements of the Holy Spirit in our new birth, but we can be sure of our new birth by faith in Jesus Christ. There is mystery involved in our new birth (John 3:8). Jesus taught that people must be born again to enter the kingdom of God (John 3:5). It is a work of the Holy Spirit changing our hearts to believe in Christ (Romans 10:9).
The Bible confirms what Spurgeon clearly explained. "Whoever believes that Jesus is the Christ is born of God, and everyone who loves Him who begot also loves him who is begotten of him" (1 John 5:1). If you are born again, faith in the Lord Jesus Christ is sure evidence.
If you are born again, you believe that Jesus is the Christ. You believe the gospel of Jesus Christ. He died for your sins. He is risen from the dead as your Lord (1 Corinthians 15:1-4). The written word of God and your faith in Christ is the evidence. That's certainly true, if you are born again.
If you are born again, the sure evidence is believing in Christ. Jesus is the Christ, the promised Messiah in the Old Testament and the Christ of the New Testament. New birth finds evidence by faith in Christ. That's the reason Spurgeon said, "You are born again if you believe Jesus is the Christ."