“They are teachers who point to their teaching or show some particular way. In all of these, there emerges an instruction, a way of living. It is not Zoroaster to whom you turn. It is Zoroaster to whom you listen. It is not Buddha who delivers you; it is his Noble Truths that instruct you. It is not Mohammed who transforms you; it is the beauty of the Koran that woos you. By contrast, Jesus did not only teach or expound His message. He was identical with His message. ‘In Him,’ say the Scriptures, ‘dwelt the fullness of the Godhead bodily.’ He did not just proclaim the truth. He said, ‘I am the truth.’ He did not just show a way. He said, ‘I am the Way.’ He did not just open up vistas. He said, ‘I am the door.’ ‘I am the Good Shepherd.’ ‘I am the resurrection and the life.’ ‘I am the I AM.’ In Him is not just an offer of life’s bread. He is the bread. That is why being a Christian is not just a way of feeding and living. Following Christ begins with a way of relating and being.”
― Ravi Zacharias, Jesus Among Other Gods: The Absolute Claims of the Christian Message
I imagine it’s hard for someone, generally, to understand when another person talks about “having a personal relationship with Christ”. The quotation by Ravi Zacharias from his book noted above provides some explanation for a statement like that, but I suspect it isn’t enough.
Can we be certain of God s existence? The short answer is, no. If the question is whether we can have something like mathematical certainty or proof, we have to answer that question in the negative. There is no evidence, no proof or argument that can provide certainty that God exists for finite beings such as ourselves.
Such evidence, proof or argument would have to be built on premises that are 100% certain, and that kind of certainty is impossible for beings that are not all-knowing. The best we can do is to put forth evidence, proofs and arguments that suggest a probability that God exists – to show that the likelihood is more probable than not that God exists.
To this extent, doubt is the common experience of saints and sinners alike.
To put this another way: Can we be sure that God doesn’t exist? The only certainty is that we can’t be certain.
Many believers have doubts, and many nonbelievers have their own doubts.