1. There is not nearly enough evidence to convince me that God exists.
First, this objection is necessarily personal. It is possible to claim that our personal, subjective threshold for evidence has not been met, but this fact would only disprove God's existence if we were certain that our personal standard of proof is correct. How do we know it is correct? And what do we even mean when we talk about the "correct" standard of proof?
A second question deals with the burden of proof. The skeptic often presumes that the burden of proof lies with the theist to prove that God exists (the evidence must "convince me" to move from atheism to theism). But why should the burden of proof not lie with the skeptic to convince the theist that God does not exist? We might answer that "extraordinary claims require extraordinary evidence." But then we are left asking who determines the definition of "extraordinary." People with different worldviews may share many presuppositions about the intrinsic likelihood of certain events, but in other areas there will be a genuine lack of agreement about what is intrinsically likely or unlikely. For instance, an atheist might consider a miracle wildly implausible. On the other hand, a theist would consider the creation of the universe ex nihilo by anything other than God wildly implausible. We need to recognize that our presuppositions are intrinsic to our worldview and are truly presuppositions. They determine what we consider plausible and implausible, prior to our examination of the evidence. Although this truth may seem unremarkable when we share basic assumptions about reality, it makes an enormous difference when we come to issues that touch on these presuppositions directly (see Resurrection and Worldview for one such example).
Finally, this objection actually addresses the theist's warrant to believe that God exists rather than the question of whether He exists. In other words, it says that the evidence is not sufficient to compel me to believe in God. But our warrant to believe in a fact does not affect the truth or falsehood of this fact. For instance, physicists in the 1910s had little warrant to believe that quantum mechanics was true. But it was true! So even if we grant that theists are not warranted in the belief in God's existence, He could exist nonetheless.
Short answer: first, this statement is personal and subjective. Second, this statement assumes that the burden of proof ought to fall on the theist; how do we know this? Third, there is a difference between claiming that belief in God is unwarranted (i.e. is not reasonable based on the evidence at hand) and that He does not exist. See also The Necessity of Faith and Resurrection and Worldview.
~ Neil Shenvi