How is it that you know you are not just a butterfly having a dream?
How do you know the sun will come up tomorrow?
How do you know you are going to heaven?
The answer to these--and so many more questions--is that Jesus Christ rose from the dead three days after His crucifixion.
You might say that you are going to heaven because Christ died for your sins. This is not a wrong answer, but it is not complete. Jesus died for your sins--and rose again the third day!
Thousands of criminals were executed by Roman crucifixion over the years of the empire. Enthusiastic friends of any one of them might make the same claim. "Hey, Simeon said he would die for my sins, and I believe him." What's to prove him wrong...or right? He may have died right enough, but what evidence is there that Simeon's death, or Christ's death, had any significance for you?
The only One who can forgive sins is God. And the only One who can raise the dead is also God. Christ was declared to be the Son of God with power by the resurrection. (Rom. 1:4) "Christ died for our sins, and he was buried and he was raised again on the third day, according to the Scriptures." (I Cor. 15:3, 4)
Without the resurrection of Christ, we would be left to blind faith--the kind of faith unbelievers smirkingly think we Christians exercise. Faith is not just wanting something to be true. Christian faith is based on evidence that we consider trustworthy. That's the way human beings think. Christian faith is not blind faith. It is faith in facts. Not much different than faith that the sun will rise tomorrow that is based on facts about our universe and about earth's rotation.
But Christian facts include those that are revealed in the Bible. Unbelievers are denied access to all this data by choice. They think it is no loss, because they suppose the Bible is made up of fairy tales and other stuff that requires blind faith.
Christians believe the Bible because Jesus said it was true. He said the Scriptures cannot be broken. He said in that book we have eternal life. And He also said that the Scriptures speak of Him. The thing is, Jesus predicted His death by crucifixion and His resurrection three days later. He taught it over and over again. Then these same disciples whom He taught were caught by surprise and were discouraged and confused by His death. Moreover they were shocked out of their proverbial socks to see and touch the risen Christ. When the apostle Paul wrote to the Corinthians in about 55 AD, he mentioned an occasion on which more than 500 people saw the resurrected Christ at the same time. This was but 20 some years after the event, but no one came forth to challenge that claim. The tomb was empty. The body was nowhere to be found by His enemies.
There are many who began to read the Bible just to discount the Christian faith who had their head (and heart) turned by the power of the Holy Spirit as they read the Scriptures. Please don't mock until you have read it for yourself. Honesty will then require you to at least admit that the accounts of Jesus' death and resurrection were written by sober men who themselves believed the resurrection to be fact.
Of course we know that it is impossible for dead people to come alive again. Brain tissue begins to deteriorate within minutes, and the rest is not far behind. Every Christian also knows this. The only possible exception to this scientific fact must be accomplished by God, who created human flesh in the first place. It had to be impossible in order for God to make His point. Christ is risen, and therefore He is right. No one else in the history of the world can make that claim. It's not that we Christians are light minded dolts who swallow every story told them. The difference between being a Christian and not being one, is not a matter of intelligence. It comes down to a different source of data with which to make informed decisions.
If you're not a Christian, and you are reading this (of course you are), my plea is simply that you would read through the Gospel of John, and see if God is speaking to you in these words.