It's a simple and fair question. But the answer defies human logic, reasoning and experience.
We experience things through our physical senses. Our eyes capture the light reflected from physical objects. Our ears pick up the vibrations from sound waves. Our fingertips gauge the texture and hardness of the things we touch.
We live in a physical world with its four known space-time dimensions of length, width, height (or depth) and time. The God of the Bible, however, dwells in a different dimension—the spirit realm—beyond the natural perception of our physical senses. It's not that God isn't real; it's a matter of Him not being limited by the physical laws and dimensions that govern our world (Isaiah 57:15). He is spirit (John 4:24).
Notice what the Scriptures reveal about this God who is not bound by space and time.
Jesus Christ as a human being had a physical body. Like ours, His was subject to injury, pain and death. The four Gospels record that He was scourged and crucified. Several of His followers took His brutalized body, wrapped it in strips of linen and sealed it in a tomb. There was no doubt Jesus was dead. His body lay in the tomb for three days and three nights, watched over by a detachment of guards.
But it was not to remain so. A minor uproar ensued at the end of the three days when some of His followers came to the tomb—only to find it empty. They would be in for an even greater surprise!
That evening His disciples gathered in a room, with the doors firmly shut because they feared for their lives, when “Jesus came and stood in the midst, and said to them, ‘Peace be with you'” (John 20:19). Their beloved teacher, whom they had seen killed and entombed, suddenly materialized inside a locked room and greeted them! Lest they think He was an impostor, He showed them the nail punctures from His crucifixion and the spear wound in His side.
The resurrected Jesus was no longer bound by physical factors. He effortlessly entered a closed room and revealed Himself to His disciples. They recognized the physical impossibility of a fleshly body passing through walls. Eight days later He repeated the miracle for the benefit of the disciple Thomas, who hadn't witnessed the earlier appearance (John 20:26). Days later, in another miracle, He defied gravity, ascending into the sky in the sight of all His disciples (Acts 1:9).
Scripture reveals that God lives outside the bounds of time as we know it (Isaiah 57:15). We read that our awesome destiny was planned “before time began” (2 Timothy 1:9; Titus 1:2) and “before the creation of the world” (Ephesians 1:4; 1 Peter 1:20, NIV).
“By faith we understand that the universe was formed at God's command, so that what is seen was not made out of what was visible” (Hebrews 11:3, NIV). In other words, the physical universe we see, hear, feel and experience was created not from existing matter, but from a source independent of the physical dimensions we can perceive.
This does not mean God the Father and Jesus Christ never reveal Themselves to people. The Scriptures are a chronicle of God's interaction with—and care and concern for—men, women and children through the centuries.
Many people reject the Bible, the Gospels in particular, because it describes many miraculous occurrences—dramatic healings, resurrections, fire from heaven and spectacular visions, to name a few. They believe these things are impossible because they defy human experience and the laws that govern our physical existence. They thus conclude that biblical accounts of such things cannot be true.
Regrettably, they fail to consider that God the Father and Jesus Christ can operate beyond the bounds of the physical laws that govern the universe. A God who can bring the universe into existence can certainly perform miracles such as those found in the Scriptures!
Where does this leave us? Will we believe the many witnesses God has provided, or will we insist on some kind of proof He provides us personally before we believe? Jesus' words to Thomas in John 20:29 are also clearly intended for us: “Because you have seen Me, you have believed. Blessed are those who have not seen and yet have believed”!