Can we really be sure that God exists?

Yes. There is sufficient evidence to prove God. There are ample proofs in nature that there is a creator, and the truths of the Bible assure us that this creator is the God Christians worship and serve. “Theism” (the belief that a creator exists who not only made the world but who also has acted in this world) is defensible on philosophical, historical, scientific and experiential grounds. Further, all of the possible objections against the existence of God can be sufficiently answered. Based on these lines of evidence and the absence of legitimate counter-evidence, it is rational to conclude that God certainly must exist.