Yes, all have sinned against God, Romans 3:23.
Without Christ, forgiveness, reconciliation and peace with God are not possible. We cannot get rid of our sin on our own, and cannot cover, or atone for it by good deeds. Only Jesus, and his saving death on the cross, can do this for us.
If someone rejects Jesus, there is no other way their sin can be forgiven, Acts of the Apostles 4:12; they have rejected the only Way to God, John 14:6. So when they die and stand before God, they will stand before him as an unforgiven sinner.
But if people have never heard the Gospel, never been told that Jesus is the only Saviour and only way to God, how can they be judged for not accepting it? That would be unjust - to condemn someone for not asking for forgiveness for their sins when they didn't know that they could.
Because they sinned. Appreciate the gift we have been given to have heard the gospel and accepted it. We don't deserve it, we all deserve hell. Ultimately those people are getting what they deserved and what we deserve, we are just given a gift. That should be utterly humbling. I understand your compassion, but you have to have faith that God's judgments on this world are just, and when you are with Him after shedding the flesh, you'll have a new perspective, you will see that it is much more than them just not accepting Jesus, they have a bunch of secret sins, and are getting what they deserve and what they have earned.
While we are wrong to disagree with God's judgments, it's understandable from our limited perspectives to do so, because we are not perfect, it's in our nature to be wrong. Sometimes we think if it were up to us, we'd do things differently. I know I wouldn't send someone to eternal punishment, I'd just annihilate them forever. Just non existence. But God has a reason for eternal punishment, and I only hope that I'll understand it someday.
The same goes with some things promised about the new earth. Some things I really enjoy, that are not sinful, won't be present in the new earth, and sometimes those things make me anxious. Marriage (Matthew 22:30), the oceans (Revelation 21:1), a star filled night sky lit by the moon and stars alone (21:23), a sunrise or sunset (same Revelation scripture just back there).
But all I can really do is trust that even without these things, the new creation will be better, I can only trust God on it.
Many would say that we inherit Adam's sinful nature.
Some say that babies have this nature and if they die before a certain age, there is no hope.
I believe, personally, if they were to die before they can hear the Gospel, God has mercy.
Sinful nature, yes, inherit his sin no. That's a false doctrine of Original Sin. We inherit the capability and propensity to sin. We choose it. We do wrong things at first as young children because we know no better, we don't know what we're doing is wrong, but later we learn the difference between wrong and right... and CHOOSE to do wrong. That is where we die spiritually.
Romans 7:9-11
Before that though, we're alive spiritually, and if a child dies at that time they haven't sinned, so they are of the kingdom of God
Matthew 19:14
Matthew 18:3
So God, who is love, 1 John 4:8, who is perfect, Matthew 5:48, who has great compassion, Psalms 51:1, Exodus 34:6 and whose compassion never fails, Lamentations 3:23, will condemn someone to eternal punishment because no Christian has ever told them about Jesus and how they can be saved and forgiven for their sin?
I don't believe that about God.
Sin cannot enter the kingdom of God. So either a person has to be sinless, like an innocent young child, or, they have Jesus' righteousness substituted for their own through Jesus death, burial, and resurrection.
Only way to have that substitution is to have faith in Jesus Christ.
The way to save those people who haven't heard the Gospel.. is to teach them the Gospel.. that's why there's so many missions around the world.
Are you saying that everyone's name is in the book of life to begin with, it is removed when they sin, and then put back in when they become a Christian?
What happens when a Christian sins - is it removed again until they repent? Is it written only in pencil for a while, then inked in when they die and sin is no longer possible?
No I do believe in eternal security. Once your spirit has been quickened when you are saved you're back in the book of life and there is only one thing I know of that can have it be removed.
Revelation 22:19
I believe that once you are saved, your spirit is a "new creature" (2 Corinthians 5:17), and that spirit won't be condemned (barring removing words from Revelation to change the meanings to deceive people) (John 5:24). However, when you're saved, does your flesh change? Do you instantly get a new body? No. That flesh is still the same sinful flesh you had before you were saved, and yes, it will be tempted and it will sin. Romans 7 shows the Apostle Paul's personal struggles with sin, because his body is carnal and prone to sin. Galatians 5 goes into it as well. This struggle between flesh and spirit that persists after being saved. You hate sin, but your flesh still wants to do it.
So while your spirit is new, and won't be condemned, and you still sin in your flesh, God doesn't condemn your spirit, he punishes your flesh. Hebrews 12:5-8 refers to it as scourging and chastisement. You do something wrong as a Christian, God punishes your flesh on this earth to correct you.
If a sinful Christian was "delivered to Satan", I am certain that Satan would not let them go again. Their soul would not be saved, it would belong to the devil.
The spirit/soul already belongs to God, when they deliver a sinning Christian to Satan it's the flesh that Satan destroys, He doesn't get the spirit. The spirit goes to the Lord. That's what the verse says, destroy the flesh so the spriit can be saved.
1 Corinthians 5:5 read it yourself, read 1 Corinthians 5 for context about a Christian in the church who is committing adultery.
We all sin as Christians.
I see no Scriptures which say that Jesus's death on the cross was not enough, and God continues to punish us for those sins.
So if a Christian is ill, is that illness a punishment for their sin?
That's true, but our flesh is still subject to death.
and no not all illness there are biological causes too. Or it can be for God's glory such as the blind man that Jesus healed. But it can be chastisement from the Lord. We shouldn't judge like Job's friends, but acknowledge that it can be a possibility. I don't use it as a way to say that "they're not saved" I actually consider chastisement of a person who professes to have faith in Jesus but walking contrary to God (IE you know for fact they're getting drunk, using drugs, committing fornication, etc) and they have nothing but illness and problems in their life that that's actually a sign that God is "dealing with them as a son", a sign that they probably are saved. But I don't necessarily judge a person who says they're saved , has all these illnesses and problems to necessarily be doing something wrong, I'm not going to say "what are you doing wrong to earn the chastisement?" Cause it could be for another reason. That's just if they tell you they're an alcoholic and they have all these problems and they're a Christian, then it's probably chastisement. Does that make sense?