Stephen Hawking, the world-renowned physicist tells us there's no heaven. This is hardly an original thought. The Buddhists and Hindus and other religions have opted out of having a coherent theology of heaven since the beginning. The ancient Jews didn't really have a clear idea either, and the Jewish sect of religious leaders called The Sadducee didn't believe in the resurrection. Jesus brought in some ideas about a mansion he would prepare for his followers to which he would go after his death and resurrection, but his own friends gave him that blank stare like "you've got to be kidding" (see John 14). In the early days of the spread of Christianity Paul traveled everywhere speaking about the resurrection of Jesus, even holding conference with scholars in Athens, one of the top centers of learning in its day. He sort of lost his audience when he shifted the discussion from this world to the next, claiming that Jesus' resurrection from the dead was a physical reality. Those guys may not have known Newtonian or Quantum physics, but they knew enough to know that dead people don't come back to life. So what did they do? They must have hooted at Paul with peals of laughter and elbowed each other exchanging knowing glances to say, "Can you believe this guy" and "see what they grow in the backwaters of the empire."
As if in honor of those ancient Greeks and Jews, a modern round of enlightened folks continues to make certain pronouncements to the effect that none of that God-stuff exists, never did, never will, forget it, get over it. Unlike the ancient guys who only had Plato and Socrates and Aristotle, we have particle accelerators and nuclear bombs, which means if there really was still any doubt that God does not exist, we've put out that flickering candle by probing the innermost nooks and crannies of sub-atomic particles. Hawking likes to say that the whole universe is here because gravity does odd things with itself, spawning universes. It's like in the child's book I read to my son, puppies dig in the dirt because, well, puppies are like that...gravity spawns the universe because gravity is like that.
So the ancient skeptics didn't have modern physics, but they had eyes and ears and brains so when they heard a dead person came back to life after three days they thought something smelled rotten. But the early followers of Jesus kept insisting that's exactly what happened. However, they did not try to produce physical evidence in the way we think of it (radioactive rocks from the tomb, a shroud with Jesus' picture on it, the latest issue of Archeological Times). What if a person rises from the dead, how would you prove it short of bringing the resurrected person to your next cocktail party? You could get the death certificate and then go back a couple of weeks later with the risen person for a check-up complete with MRIs and a blood test. The next best you could do is call upon eye witnesses. That seems to be exactly what the early church depended upon: the original Apostles, Paul who claimed to have seen Jesus in a special moment, and 500 others.
In addition to offering eye-witness accounts, the early church repeatedly went back to the Old Testament scriptures and pointed out the amazing ways in which texts written hundreds and thousands of years before the first century had their fulfillment in Jesus of Nazareth. The alleged fulfilled prophecies, numbering in the dozens, were either an amazing coincidence or part of a divine conspiracy. Coupled with the pesky eye-witness reports that after a brutal death on a Roman cross, Jesus came back to life, the early believers ruled out coincidence.
Back to Athens.Paul talked about the eye-witness accounts and the Old Testament prophecies. We can almost hear the ancient philosophers shout with the modern skeptics, "Where's the evidence?! Present us the living, breathing dead man, that is, the guy that was dead but isn't. "Yet others in the crowd listened to Paul's message and believed. For some folks a second-hand report was insufficient, for others it was sufficient, they believed and followed Jesus.
God, as pictured in the bible, is not a part of his creation. He exists independently of it, outside it. Physicists can measure the weight of atomic particles and doctors can take a person's temperature because particles and waves make up the physical cosmos. But God is spirit. Humans have a spirit too. The spirit can act upon the physical world, but the physical tools can't access spirit. Under normal circumstances, there can be no physical evidence for something existing outside the physical realm. What we do have are personal accounts, recorded in stories. Those reports tell about times when the spiritual interacted with the physical. Those times were when God chose to act. He chose to reveal himself. No one can force God to repeat them. They are a bit like the feelings and thoughts a man has in that first moment he realizes he loves his wife-to-be or in the moment his child enters the world. It's a matter of one person being revealed to another. In that moment you believe and you know and you experience something that might be said to resemble, for lack of a better word, heaven.