When we answer this question with scripture, it is much different than many in the Christian world would answer. Jesus said in John 3 that we must be born again of water and Spirit to see and enter into the Kingdom of God. Matthew, Mark, Luke, and John point us to Acts which is the birthplace of the New Testament Church.
On the Day of Pentecost (Acts), the Holy Ghost was sent by God who came to earth as Jesus Christ – God manifest in the flesh who died on the cross for our salvation. Jesus told the disciples to go to Jerusalem and wait for power from on high. Read the history of the New Testament church in Acts 1 & 2. Peter preached “God has made this Jesus, both Lord, and Christ.”
Acts 2: 37 – “Now when they heard this, they were cut to the heart, and said to Peter and the rest of the apostles, ‘Men and brethren, what shall we do?’” Vs. 38/39 – “Then Peter said to them, ‘Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit. For the promise is to you and to your children, and to all who are afar off, as many as the Lord our God will call.’”
As we look at the New Testament, we must understand a simple truth. Matthew, Mark, Luke, and John recorded the birth, the life/ministry, death, burial, and resurrection of Jesus Christ. Isaiah 9:6 informed us that this child would be born, and a Son is given, and His name would be, “Wonderful, Counselor, Mighty God, Everlasting Father, Prince of Peace.” This is the simple truth that Jesus Christ is the Almighty God manifest in the flesh – One God.
In Matthew 28:18 – 19 “And Jesus came and spoke to them saying, ‘All authority (power) has been given to Me in heaven and on earth. Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age.’ Amen.”
Pay attention! Jesus has all authority in heaven and in the earth. If Jesus has all authority/power, what power does God and the Holy Spirit have? This seems like a good question for those who claim three persons in the Godhead. What we know by the Word of God is that Jesus was God manifest in the flesh. Immanuel means “God with us.”
Vs. 19 says to make disciples baptizing them in the name – Father, Son, and Holy Spirit are titles they are not a name. The name is Jesus Christ. No one was baptized in this passage of scripture.
New Testament salvation was revealed by the events of Acts 1 & 2 – read the rest of the history in the following chapters in Acts. The books of Romans through Jude in the New Testament are letters written to the new believers who had been born again of water and Spirit the same as happened on the Day of Pentecost. They are private letters written to the born-again believers, not to sinners.
The Christian world takes scriptures written to believers who have already received their new birth experience and tell sinners Romans 10:9 “that if you confess with your mouth, the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved.” The Roman church had already confessed with their mouth through salvation as in Acts 2:38. Paul explains to the Roman church as you read the entire chapter that the gospel of peace will be heard through preaching. How will they call on Him? By calling on the name of Jesus Christ through baptism as was done on the Day of Pentecost.
As you read through the book of Acts, you will find new believers were baptized in the name of Jesus Christ and received the gift of the Holy Spirit speaking in tongues as on the Day of Pentecost. Romans 10: 13 says “For whoever calls on the name of the LORD shall be saved.” Calling on the name of the LORD is through baptism. This does not mean if we say, “Lord!” that we will be saved. We must learn how to rightly divide the Word of Truth!
Again, the books of Romans through Jude were letters to believers that had been born again of water and Spirit. They are letters explaining to the new believers how they ought to behave and be holy as God is holy. Salvation is in the book of Acts not in the book of Romans – the Roman church already had salvation through repentance, baptism in Jesus name, and the infilling of the Holy Ghost. Paul was explaining their salvation in Christ Jesus.
There is one God our Creator. Jesus Christ was the Word that became flesh and dwelt among us – John 1. The Holy Ghost is God in us the hope of glory that we receive by the initial sign of speaking in a heavenly language as happened on the Day of Pentecost. These are not three persons! God is a Spirit! The only person we will see in heaven is Jesus Christ who is the King of Kings and the Lord of Lords!
When you read anywhere in scripture about the ‘right hand or throne of God’ – it means in the Almighty Power of God. There is only one God! Ephesians 4:6 King James Version (KJV)
6 “One God and (and in Greek kai means even) Father of all, who is above all, and through all, and in you all.” Note this scripture was written to the believers at Ephesus who had already experienced their personal Pentecost salvation of water and Spirit. This one God who is the Father of all entered their hearts through the baptism of the Holy Ghost.
You may be a believer in God and that is wonderful. But to be saved, we must obey the scripture, Acts 2:38, and experience our personal salvation through repentance, water baptism in the name of Jesus Christ, and the infilling of the Holy Ghost. God came to earth in the flesh of Jesus Christ to pay the price of our sins on the cross. Through salvation, we are justified before God for our sins. We are sanctified throughout our life as we follow God’s example. We will be glorified when Jesus Christ (who is God) returns in the clouds to take His Bride (coming back for His namesake) to heaven.
What must we do to be saved? Obey the simple plan of salvation of Acts 2:38. The demons believe there is one God and they tremble. We must do more than believe or confess. We must obey Jesus who said (John 3) be born again of water and of Spirit to enter into the Kingdom of God!