Do we need to believe in Jesus as the Son of God to be saved?

from the old testament

• The Old Testament established that it is the Lord alone who saves. He Himself said, “I, I am the LORD, and besides me there is no savior” (Isaiah 43:11). Salvation requires calling on His name: “And it shall come to pass that everyone who calls on the name of the LORD shall be saved" (Joel 2:32).
• The Old Testament also indicates that the coming Savior would be divine, being called titles such as “Mighty God” (Isaiah 9:6). Jesus' title “Lord” reflects more than human authority; it points to His divinity.
• The Lord instituted the Mosaic sacrificial system because "it is the blood that makes atonement by the life" (Leviticus 17:11). He was teaching the Israelites that sin required blood (death) to point them to a future sacrifice. In Isaiah 53, discusses that sacrifice.

from the new testament

• Matthew opens by explaining to the Jews in his day that Jesus was the expected son of David (Matthew 1:1) and also Immanuel, meaning “God with us” (Matthew 1:23).
• Believing in Jesus as the Son of God is connected with salvation. John 3:16–18 says, "For God so loved the world,[a] that he gave his only Son, that whoever believes in him should not perish but have eternal life … Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God.”
• This is why Paul would later say, “if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved” (Romans 10:9). He follows this by quoting from Joel 2:32, saying, “For ‘everyone who calls on the name of the Lord will be saved.’” He explicitly chose to connect confessing “Jesus as Lord” with a verse that said that salvation was achieved by confessing in the name of Yahweh, thereby connecting Jesus to God’s personal name (cf. 1 Peter 3:15). So, confessing that Jesus is Lord is more than an exalted title; it's a reference to His divinity. Denying His divinity is not to confess Him as Lord and thus is not to be saved.
• Jesus added on true humanity (Philippians 2:6–7), so He has two natures, one fully divine and one fully human. In His humanity, Jesus lived perfectly and was the promised Suffering Servant Isaiah prophesied about (1 Peter 2:22–25). By being the God-man, Jesus was able to serve as the mediator between God and humanity, providing the only bridge to salvation (John 14:6; 1 Timothy 2:5).
• Explaining the Trinity perfectly isn't tied to salvation, but willfully denying Jesus as the Son of God is to reject salvation. John said, “Who is the liar but he who denies that Jesus is the Christ? This is the antichrist, he who denies the Father and the Son. No one who denies the Son has the Father. Whoever confesses the Son has the Father also” (1 John 2:22–23).

implications for today

We all have "dealbreakers." Maybe it's the salary we're willing to accept on a job offer. Or maybe it's about how we're treated in a friendship. A dealbreaker for salvation is recognizing that Jesus is the Son of God, the only One capable of dying for our sins. Without that, there is no salvation.

When Jesus came to Earth, He took on a human nature. Being fully God means that He is perfectly holy. Being fully human means that He is like us, but without sin. By being the perfect God-man, then, Jesus stood between God and humankind. When the Father poured out judgment on Jesus for the sin of those who would repent, He made a path of reconciliation through Himself to God.

This should make us grateful that we have a way to God. Now, everyone who believes that Jesus is who the Bible says He is—fully God and fully man—will be saved. Jesus’ death will be counted as punishment for their sin, and they will be called children of God (John 1:12).