To adequately consider this question, you must first understand the Biblical concept of God. When we think about God, we are not thinking about a Being alongside other beings in the universe, for God stands behind all reality as its source and foundation. When the Russian cosmonauts stated that they didn’t see God out there, they were making a fundamental error. C.S. Lewis commented that such a statement was similar to Hamlet looking for Shakespeare in the attic of Elsinor Castle.
God is the uncaused cause who has always existed in eternity and is "non-contingent". (See Who or What Created God? for a brief discussion of the concept of non-contingency.) God is the background context of our lives and, as one philosopher put it, God is the inescapable "all-conditioner". The Apostle Paul in his speech to the intellectuals in Athens quoted a Greek poet who stated, "In Him we live, move, and have our being".
God is the creator of the universe and time—the source of all being and consciousness. God is beyond our comprehension, and, therefore, cannot be held at arm’s length and evaluated with cool objectivity or be judged by human standards.
Along with God's complete otherness and transcendence, the Bible portrays encounters with God as overwhelming experiences. In the Bible's account of the Exodus, the Hebrews are portrayed as being terrified by God's presence on Mount Sinai.
“Now when all the people saw the thunder and the flashes of lightning and the sound of the trumpet and the mountain smoking, the people were afraid and trembled, and they stood far off and said to Moses, “You speak to us, and we will listen; but do not let God speak to us, lest we die.” (Exodus 20:18-19)
The prophet Isaiah describes his vision of God in the temple at Jerusalem exclaiming,
"Woe is me!". "For I am lost! For I am a man of unclean lips, and I dwell in the midst of a people of unclean lips; for my eyes have seen the King, the Lord of hosts." (Is 6:5)
In spite of his suffering, Job also reacts with utter humility when God appears to him stating,
"My ears had heard of you, but now my eyes have seen you. Therefore, I despise myself and repent in dust and ashes."
People who ask why God does not appear to us more directly do not know what they are asking and could not cope with the reality of God's direct presence if God granted their request.
There is also the related truth about human freedom. If God was immediately present to us, we would be compelled to respond to God and conform to His will. To be in the presence of God is to be directly subject to God, the creator and sustainer of the universe. In that case, we would have no choice but to obey. Those who would, under normal circumstances, be inclined to ignore God and live apart from Him would be confronted with God's unavoidable presence. Free will (the ability to act in terms of one's own inclinations) would be gone. But God desires that we freely respond to His initiative towards us. He does not want automatons or robots that have no choice but to do His will. God's hiddenness and silence preserves our freedom to respond or not respond to Him.
Finally, when God came into the world in the person of Jesus, God showed himself directly to human kind in a way people could relate to and understand. However, only a subset of the people living in first century Palestine actually saw and interacted with the historical Jesus. Those who did witness His life and teaching, saw a demonstration of the character of God. But for all of us who have lived after the first century, we can meet Christ only as we respond in faith to the gospel accounts of his words and actions. Therefore, we must trust in the testimony of eyewitnesses. The disciple, Thomas refused to believe that the crucified Jesus had risen from the dead unless he could actually see Jesus and put his hands in his wounds. Jesus later appeared to him and the other disciples. Jesus addressed Thomas saying,
"Put your finger here, and see my hands; and put out your hand, and place it in my side. Do not disbelieve, but believe.” Thomas answered him, "My Lord and my God!" Jesus said to him, "Have you believed because you have seen me? Blessed are those who have not seen and yet have believed." (Gospel of John 20:27-29)