From the wilderness of Sin the whole congregation of the Israelites journeyed by stages, as the Lord commanded. They camped at Rephidim, but there was no water for the people to drink. The people quarrelled with Moses, and said, ‘Give us water to drink.’ Moses said to them, ‘Why do you quarrel with me? Why do you test the Lord?’ But the people thirsted there for water; and the people complained against Moses and said, ‘Why did you bring us out of Egypt, to kill us and our children and livestock with thirst?’ So Moses cried out to the Lord, ‘What shall I do with this people? They are almost ready to stone me.’ The Lord said to Moses, ‘Go on ahead of the people, and take some of the elders of Israel with you; take in your hand the staff with which you struck the Nile, and go. I will be standing there in front of you on the rock at Horeb. Strike the rock, and water will come out of it, so that the people may drink.’ Moses did so, in the sight of the elders of Israel. He called the place Massah and Meribah, because the Israelites quarrelled and tested the Lord, saying, ‘Is the Lord among us or not?’ -Exodus 17:1-7Here were people who had certainly seen signs and wonders. They saw the 10 plagues, followed a pillar of cloud/fire, saw the Red Sea parted, and received manna from Heaven. Even with all of these signs, they still needed more to believe that God was among them. They still needed proof that God was going to provide for them. They ask, "Why did you bring us out of Egypt, to kill us and our children and livestock with thirst?" This question almost answers itself. If God had delivered them that far, why abandon them at Rephidim?
It seems that the quest for proof of God's existence only leads to us needing more proof. God wouldn't bring us this far only to abandon us where we are. Let us learn to live our lives as Christians without the undeniable proof. Part of having faith is believing without that proof. Have faith that God is still with you.