The Gospel of Jesus Christ is this, God IS and He is real, true, holy, righteous, and just. He created mankind (human beings) to have a pure relationship with Him because He loves us.
However, when God created the first man (Adam), giving him commands to obey, Adam disobeyed and sinned (Genesis 3:6,7), and as a result from then on all mankind was separated from God and in sin (Romans 5:12). God says,
“For all have sinned, and come short of the glory of God” (Romans 3:23)
And also, “Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned” (Romans 5:12)
And again, “If we say that we have no sin, we deceive ourselves, and the truth is not in us.” (1 John 1:8)
So how can we be saved from our sins and have eternal life?
You must come to realize and admit you are separated from God and in sin.
No one is good enough to go too Heaven on their own merit. No matter how much good we do, we all still fall short of God’s requirements. Why? Because you have sin and are in sin and it separates you from God and from obtaining salvation which is eternal life.
You must realize the penalty for your sin.
“For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord.” (Romans 6:23)
“Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned” (Romans 5:12)
“And death and hell were cast into the lake of fire. This is the second death. And whosoever was not found written in the book of life was cast into the lake of fire.” (Revelation 20:14-15)
There is a consequence for your sins; which is spending an eternity of your soul in Hell separated from God.
You must truly believe in your heart and mind that Jesus Christ is real, lived on earth, died, was crucified, buried, and rose from the grave as payment for your sin.
“But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us.” (Romans 5:8)
“For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.” (John 3:16)
“And we are witnesses of all things which he did both in the land of the Jews, and in Jerusalem; whom they slew and hanged on a tree: Him God raised up the third day, and shewed him openly;” (Acts 10:39-40)
“For by grace are ye saved through faith; and that not of yourselves: [it is] the gift of God: Not of works, lest any man should boast.” (Ephesians 2:8,9)
Salvation is simply believing in Jesus Christ and putting your faith (fully believing with your whole heart and mind) that Jesus Christ paid for your sins.
“In hope of eternal life, which God, that cannot lie, promised before the world began” (Titus 1:2)
“Therefore being justified by faith, we have peace with God through our Lord Jesus Christ.” (Romans 5:1)
“That whosoever believeth in him should not perish, but have eternal life. For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.” (John 3:15-16)
When God saves you He gives you “eternal/everlasting” life – a life that will never end; a life that will last forever. So, when He saves you it is forever.
Eternal life is a gift purchased by the blood of Jesus and offered freely to those who call upon Him by faith. All those who truly believe in the Lord Jesus Christ will be saved forever. Being saved is a one-time event. All you have to do is believe in Him, turn to Him, and cry out to Him. Tell him from your heart that you want to be saved.
“The LORD is nigh unto all them that call upon him, to all that call upon him in truth.” (Psalm 145:18)
“That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.” (Romans 10:9-10)