I've never been a fan of the whole "God does not believe in atheists" thing. Of course there are people out there who genuinely believe God does not exist. Scripture itself declares that there are (foolish) people who say in their hearts "there is no God". But it is the clear teaching of scripture that those who do hold such beliefs hold them by choice. They "suppress the truth in unrighteousness". Those who do not believe in God genuinely do not believe in God, but this is not because of evidence that convinced them. This is because they do not want to believe.
The world is divided between two religions: Christianity and idolatry. Mankind generally prefers its own idolatry. We worship our own sin rather than the God who takes it away, and so as the Church rejects that which threatens our faith, so also do unbelievers reject God when He threatens their sin.
So many atheists actually admit that if they knew God existed, they would not worship Him because they don't like Him. They read the Bible and see Him judging sinners, they don't like that, and so I've actually had atheists tell me that they "would not worship IT". And that's not my emphasis there, they genuinely do call God an "it", and do so in capital letters just to show how much they hate Him.
Everyone in Hell will be there because they deserve it. Now, that's not saying that Christians are somehow better than everyone else, because no one in Heaven will deserve to be there. Our God actually had to die on a cross because we also deserve Hell. But everyone who goes to Hell will deserve it. "I didn't know" will not be a valid excuse.
Salvation isn't a right. Salvation is a beautiful gift that is given to us by a God who loves us. But if we reject that gift, a lack of knowledge is still not a good excuse, because it is the same sin that condemns us to Hell that causes us to choose to go to Hell. Our love of sin and hatred of God means that even if God were to perform an actual miracle in front of a hardened sceptic, they still wouldn't believe. How do we know? Look at history. How many miracles did God perform? How many people who witnessed those miracles believed?
Go to John 6, Jesus fed more than 5,000 people with a child's lunch box, but because He followed it up with a difficult spiritual teaching, they walked away saying "this is a hard saying, who can understand it?" Jesus performed a miracle, the people left. Go back even further, God rescued Israel from Egypt with 10 plagues, followed by Him appearing in a pillar of smoke, splitting the sea in half so they could cross safely, remaining as the pillar of smoke (which turned into a pillar of fire by night), feeding them with miraculous food, watering them with water from a stone, and they still turned and worshipped a lump of gold.
The depravity of man knows no end, and there is only one way out of it. Today is the day of salvation. Once you're dead, there are no second chances. You don't even deserve the first chance, so take salvation while God is offering it to you. Confess with your mouth "Jesus is Lord", and believe in your heart God raised Him from the dead, and you will be saved!