How can we be certain that the only time to choose salvation will be in this life?
Well, for salvation to happen outside of this life, it would have to happen before or after this life. Before is not an option because we are finite beings: we are not like God who has always been and always will be. We have a start date. But, like God, we don’t actually have an end date. All people will continue to live past this life, either in Heaven with God, or in Hell separated from God.
So the question then becomes, can you accept relationship with Jesus after you die?
No. You can’t.
Hebrews 9:27-28
27 Just as people are destined to die once, and after that to face judgment, 28 so Christ was sacrificed once to take away the sins of many;
When we die, we face judgement. There is no talk of any kind of middle ground place where we are offered another chance to repent from our sins and start following Jesus after death.
Luke 16:19-31
19 “There was a rich man who was dressed in purple and fine linen and lived in luxury every day. 20 At his gate was laid a beggar named Lazarus, covered with sores 21 and longing to eat what fell from the rich man’s table. Even the dogs came and licked his sores.
22 “The time came when the beggar died and the angels carried him to Abraham’s side. The rich man also died and was buried. 23 In Hades, where he was in torment, he looked up and saw Abraham far away, with Lazarus by his side. 24 So he called to him, ‘Father Abraham, have pity on me and send Lazarus to dip the tip of his finger in water and cool my tongue, because I am in agony in this fire.’
25 “But Abraham replied, ‘Son, remember that in your lifetime you received your good things, while Lazarus received bad things, but now he is comforted here and you are in agony. 26 And besides all this, between us and you a great chasm has been set in place, so that those who want to go from here to you cannot, nor can anyone cross over from there to us.’
27 “He answered, ‘Then I beg you, father, send Lazarus to my family, 28 for I have five brothers. Let him warn them, so that they will not also come to this place of torment.’
29 “Abraham replied, ‘They have Moses and the Prophets; let them listen to them.’
30 “‘No, father Abraham,’ he said, ‘but if someone from the dead goes to them, they will repent.’
31 “He said to him, ‘If they do not listen to Moses and the Prophets, they will not be convinced even if someone rises from the dead.’”
Our only chance to accept relationship with God through Jesus is in this life. There is a great chasm that has been set in place, so that those who want to go from Heaven to Hell cannot, nor can anyone cross over from Hell to Heaven.
We often have a pretty fundamental issue with understanding salvation:
WE look at it as a way to get out of something bad.
GOD looks at it as a way to get us into something good.
Salvation isn’t about us not going to Hell, salvation is about us knowing our Creator in an intimate way. Hell is what happens when WE REJECT HIM.
What about people who never get to hear the Gospel?
It's a really hard reality to face, but people who don’t hear the Gospel go to Hell.
John 14:6
I am the way and the truth and the life. No one comes to the Father except through me.
Jesus is the ONE AND ONLY WAY TO GET TO HEAVEN.
It's simply not Biblical to think that God judges people differently who have never heard the Gospel. If that were the case, it would contradict God telling us to go into all the world and share the Gospel.
So, What about Babies who die?
We don’t fully know. There are a couple different scriptures that lead us to think there is a possibility:
Romans 1:18-20
18 The wrath of God is being revealed from heaven against all the godlessness and wickedness of people, who suppress the truth by their wickedness, 19 since what may be known about God is plain to them, because God has made it plain to them. 20 For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that people are without excuse.
So this scripture is saying, even if people don’t hear the Gospel, there is no excuse because the whole world around them points to God. This can lead us to believe that there is a POSSIBILITY that God makes it plain to people who don’t get to experience the world that He is God.
John 9:41
41 Jesus said, “If you were blind, you would not be guilty of sin; but now that you claim you can see, your guilt remains.
So, there is a potential that a baby or severely mentally handicapped person who never sees their sin could still meet God after they die.
Ultimately, there is to way for us to really know for sure.
Matthew 18:3
And he said: "Truly I tell you, unless you change and become like little children, you will never enter the kingdom of heaven.