Why is believing on the Son of God important for Christians?

For Christians, belief in the Son of God is fundamental to their faith and spiritual life. As stated in 1 John 5:12, 'He that hath the Son hath life; and he that hath not the Son of God hath not life.' This passage succinctly encapsulates the necessity of faith in Christ for receiving eternal life. Furthermore, it is through believing in Christ that believers are reconciled to God, experience His grace, and possess the assurance of salvation, underscoring the vital significance of this belief.