Genesis 7: Noah was six hundred years old when the flood of water came upon the earth. The water prevailed and the mountains were covered. All flesh that moved on the earth perished, birds and cattle and beasts and every swarming thing that swarms upon the earth, and all mankind; all that was on dry land died.
Matthew 24: The future coming of the Son of Man (Jesus) will be just like the days of Noah. For as in those days before the flood people were eating and drinking, marrying and giving in marriage, until the day that Noah entered the ark, and they did not understand until the flood came and took them all away; so will the coming of the Son of Man (Jesus) be.
Going through the door on the Ark was the only way to be saved. There was only one door into the Ark. Every living thing that did not go through that door died.
It is the same today, except the door we must go through is Jesus Christ. Everyone who does not go through Jesus, meaning everyone who is not trusting (believing) in Jesus Christ alone, will die.
What does this mean? I hear people say, "I believe in God. I'm a pretty good person. I'm fine." Is that true? And what does "trusting in Jesus" mean? And why are you saying that Jesus is a door? He was a man, not a door. And aren't we all going to die anyway? What kind of story are you telling me?
James 2:19 "You believe that God is one. You do well; the demons also believe [in God], and shudder."
Why do the demons shudder? They know the true God. They believe God exists. And they know there is justice and God will punish them for disobeying Him. Knowing that God exists does not save you. Only going through the door that is Jesus Christ can save you.
WHAT IS THE STANDARD FOR "GOOD"?
Jesus said to him, “Why do you call Me good? No one is good except God alone." - Mark 10:18
“There is none righteous, not even one; there is none who understands, there is none who seeks for God; all have turned aside, together they have become useless; there is none who does good, there is not even one.” - Romans 3:10-12
No one is good except God alone. That means you are not good. Ouch! That hurts! We tend to think we are pretty good. Oh, we make mistakes, but we're not that bad. God will forgive us. That's not what scripture says. It says, "no one is good except God." It says, "there is NONE who does good." Why do we think we are pretty good, yet scripture says we are not? Because we're not using God's definition of good. God's standard is perfection. We are created in the image of God. God's character is perfect. That means our character is to be perfect... and we're not.
The Ten Commandments are not a set of arbitrary rules. They describe God's character. They describe the way we are suposed to think and act. Have you ever told a lie? Have you ever taken something that does not belong to you? (Theft) Have you looked at another person with lust or been angry at someone. Jesus defined those as adultery and murder (see Matthew 5). As scripture says, based on God's standards you are not good.
For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, so that no one may boast. - Epesians 2:8 & 9
What does it mean to trust in Jesus? In the context of what we are talking about here, it means believe in Jesus for your salvation. Believe that Jesus has both the authority and the ability to save you. Believe that you have disobeyed God and deserve justice... meaning the just punishment for breaking God's laws. Believe that Jesus took the punishment you deserve on Himself. He died in your place so you can live. That's the promise God has made. You can trust God's promises.
"By this will we have been sanctified through the offering of the body of Jesus Christ once for all." - Hebrews 10:10
"But God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us." - Romans 5:8
JESUS IS THE DOOR:
This phrase is a metaphore. Just as going through the door into the Ark was the only way to be saved from the global flood that was coming, so also is going through the "door" that is Jesus the only way to be saved from God's just punishment for sin (disobeying God). Jesus uses a similar metaphore in John 10:9 when He says, "I am the door; if anyone enters through Me, he will be saved." In this case He is talking about being a shepherd who protects His flock, with the term "flock" referring to all those who are believing (trusting) in Jesus as their Savior.
THE SECOND DEATH:
But for the cowardly [those who are afraid of what people will say or do, and thus refuse to trust Jesus] and unbelieving and abominable and murderers and immoral persons and sorcerers [includes drunkards and drug users] and idolaters and all liars, their part will be in the lake that burns with fire and brimstone, which is the second death. - Revelation 21:8
The term "second death" refers to spiritual death, total separation from God. We all will go through the first death, which is our physical death. Those who are not believing in Jesus Christ as their Savior, will not be saved from the second death. Those who repent (turn away from disobeying God) and trust that Jesus did pay the penalty IN FULL for their having disobeyed God, will not experience the second death, but will have eternal LIFE with Christ Jesus in heaven.