Mark 16:15,16
And He said to them, Going into all the world, proclaim the gospel to all the creation.
16 The one believing and being baptized will be saved; but the one not believing will be condemned.
John 3:3,5,8
3 Jesus answered and said to him, Truly, truly, I say to you, If one is not generated from above, he is not able to see the king- dom of God.
5 Jesus answered, Truly, truly, I say to you, If one is not generated out of water and Spirit, he is not able to enter into the kingdom of God.
8 The Spirit breathes where He desires, and you hear His voice; but you do not know from where He comes, and where He goes; so is everyone having been generated from the Spirit.
Romans 1:16,17
For I am not ashamed of the gospel of Christ, for it is the power of God to salvation to every one believing, both to Jew first, and to Greek;
17 for in it ( The Gospel) the righteousness of God is revealed from faith to faith; even as it is written, “But the just one shall live by faith.” Hab. 2:4
Comment
The one believing the Gospel of Christ or God and is baptized will be saved. Belief of the Gospel happens upon regeneration or generation from above or from God and baptism is an act of man that flows out of the heart from God regenerating his people unto belief of the Gospel which would explain why unbelief is what brings condemnation without mentioning baptism in Mark 16:16.
The Gospel is the power (Dynamite) of God to salvation to every (one) believing. That Power in the Gospel is effectual to his people he came to save unto belief because of the regenerating power of God. Belief is consummated in the believer because of the power of God regenerating his people with a new heart and new spirit unto belief of the Gospel of Christ Matthew 1:21, John 6:37-44, 2 Corinthians 4:6, Matthew 16:18
The Gospel is not the power of God to every(one) not believing. God has not regenerated the unbeliever unto belief of the Gospel
John 5:21
For even as the Father raises the dead, and makes alive, so also the Son makes alive whom He wills.
Verses referenced from Jay P. Green literal translation KJ3