How to know for sure you are going to Heaven:

What does the Bible say about eternity?

First, you need to understand that all fall short of God's Standard.

The Bible says: "For all have sinned and come short of the glory of God." (Romans 3:23)

Our first Step towards God comes when we understand and admit that we fall short of His standards. We do things that we know are wrong. The Bible calls this sin. If you know that you're not perfect, then you know that you're a sinner. The Bible explains that you cannot do enough good to get into Heaven. Jesus Christ himself stated “I am the way, the truth, and the life, no man cometh unto the Father but be me” John 14:6.

Secondly, there is a price to pay for sin.

The Bible says: "The wages of sin is death . . ."(Romans 6:23a)

Sinners are like workers punching a time clock. Each time we commit sin, we earn our pay. No sin is free or unpunished because the Bible says that the payment for our sin is "death." This is eternal separation from God in a terrible place called hell; a placed reserved for all those who reject God and choose to make their own payment for their sins.

Thirdly, God has PAID the price!

Romans 6:23b says: ". . . but the gift of God is eternal life through Jesus Christ our Lord."
Also, Romans 5:8 says that “God commendeth (proved) his love toward us, in that, while we were yet sinners, Christ died for us.

God did not create hell for you. He loves you enough to give his only Son (John 3:16). He does not want you to spend eternity in hell. He came to live a perfect life in your place and die a horrible death in your place through Jesus Christ. He took on Himself the full punishment for your sin, so that you would never have to pay the price. Instead, you can live forever in Heaven with Him.

Lastly, what will you do about it?

The Bible says: "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." (Romans 10:9)
"For whosoever shall call upon the name of the Lord shall be saved." (Romans 10:13)

Forgiveness that leads to eternal life comes through Jesus Christ, who rose from the dead to prove that He is the only one able to save you. However, knowing is not enough, you must receive Him. You must want to turn from your old life and enter a new life with Jesus Christ—a life that begins when you sincerely and openly ask Him to save you.