What does the Bible mean by miraculous birth?

The concept of miraculous birth is illustrated in the account of Abraham and Sarah, whose natural inability to have children reflects our spiritual inability to choose God. In Romans 9:9, the phrase 'children of promise' points to those born not of human flesh but of the Spirit. This parallels the teaching in John 3:5-6, where Jesus explains that one must be born of water and the Spirit to enter the kingdom of God. This miraculous transformation is essential for salvation, indicating that it is God who initiates and completes the process of bringing a sinner to faith in Him.