"HUMANS generally define existence in terms of time, space, and matter."
But consider, An ultimate Creator must necessarily be unique, not dependent on any of these things, because he created them. Human definitions are not laws that must be obeyed by the universe, or by anything or any One over which humans do not have control.
Almighty God has set in place the most effective way in which we can approach him:
Acts 17:26, 27
26 "And he made out of one man every nation of men to dwell on the entire surface of the earth, and he decreed the appointed times and the set limits of where men would dwell, 27 so that they would seek God, if they might grope for him and really find him, although, in fact, he is not far off from each one of us."
So we don't make the rules on how to approach our Creator. He makes them, because he is searching for those who will worship him in spirit and truth. John 4:23
Millions of people throughout the years have found him and have made efforts in faith to get to know him, serve him and obey him.
Other people tell lies about the one true God, because they are not willing to be accountable to him. The Israelites of Moses' day saw the ten plagues, crossed the Red Sea on dry ground, and saw the destruction of one of the most powerful armies of that time when the Red Sea drowned its soldiers. And yet, many of that generation refused to obey God's law, and even wanted to go back to Egypt rather than recognize their accountability to God.
Many people today deny that God exists, not because there is no evidence, but for the same reason that this faithless crowd had, who miraculously escaped slavery in Egypt. Many people do not want to acknowledge that their Creator exists, and that they are accountable to him, despite the preponderance of the evidence that he does exist.
We have to be willing to humbly, sincerely, honestly seek him, and he will let himself be found - and he is not far off from each one of us.