there are two ways to get to heaven according to scripture
1. The law (works) Moses, Paul and James gave us the requirement if we are to get to heaven this way. Jesus said it best, when he went over the law as a means of righteousness "be perfect as your heavenly faith is perfect"
2. Grace through faith.
Jesus said it best when speaking to Nicodemus, As Moses lifted the serpent in the wilderness. so must the son of man be lifted up so that whoever believes in him will never die, but has in their possession eternal life.
The serpent represented Gods salvation. When a child of Abraham was bit and looked at the serpent in faith, he was saved. if he did not look (unbelief) he died.
We also see Gods salvation in Egypt. When the blood on a door jam saved the oldest son. God did not look at the worthiness of the child in the house. he looked at the life that was given in faith, again, those who did not put the blood (unbelief) lost their first born son
Only by grace can we overcome the world. And how does scripture say we do this?
As John said, For whatever is born of God overcomes the world. And this is the victory that has overcome the world—our faith.
Who is he who overcomes the world, but he who believes that Jesus is the Son of God? (again it is faith, He who rejects Jesus in unbelief is not born of God and does not overcome the world and is lost.
what we have to remember is we have all sinned. We have all fallen short of Gods standard. that standard is perfection. Since we all have failed to meet the requirements of salvation by works,. we are forced to look to the Lord for salvation. As the OP stated, whoever calls on the lord will be saved, with the mouth and the heart is one saved (rescued) from the penalty of sin.
the penalty of sin is death, the gift of God is eternal life.
Salvation is a gift. It can not be earned by our good deeds, By our religious works, or any works of righteousness which we have done, Only By Gods mercy can we be saved through the washing and new birth of the holy spirit
remember, the tax collector became poor in spirit, got on his knees and called out to God for salvation. He went home saved
the pharisee pumped his chest, never became poor in spirit. and thought he was saved because of how righteous he was.
He, like all people. failed to meet Gods standard. so he watered it down to make himself think he was worthy. He refused to repent and have faith, trusting only in himself.
Our work will not cause God to forgive on sin. Let alone all the sin we have, are and will commit before we leave this world. Lets turn to Christ, the only means of salvation.
Baptismal regeneration
(Born of God) faith and baptism
Jn 1:12-13 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:
13 Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.
1 Jn 5:4 For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith.
5 Who is he that overcometh the world, but he that believeth that Jesus is the Son of God?
6 This is he that came by water and blood, even Jesus Christ; not by water only, but by water and blood. And it is the Spirit that beareth witness, because the Spirit is truth.
7 For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one.
8 And there are three that bear witness in earth, the Spirit, and the water, and the blood: and these three agree in one.
Born of God by baptism