Though he did not necessarily articulate it as such, Mr. Gervais is presumably assuming the position of naturalism: the position that the only things which can be known are those which are arrived at via the scientific method. If this is the case, fine and well, but he must be prepared to surrender a good deal of ideas that he considers "truth," most notably his own atheism. As discussed above, atheism - and theism, mind you - are not positions that can be arrived at by way of the scientific method. As such, Mr. Gervais' own atheism is a matter of faith, just like the believer's theism. The two are in the same boat. The only difference appears to be that the theist is more honest about his position with all his talk about "faith" and "belief," while Mr. Gervais' game is to parade his own faith as something more - "truth, science, and nature." We should not be fooled.
If Mr. Gervais would like to make the point that one cannot use science to prove God's existence, then his point would be well-made; but he must also concede that one cannot use science to disprove God's existence, which by my lights is precisely what he purports to do. The problem for Mr. Gervais and other psuedo-scientists like him is that the question of God's existence does not belong to the province of science. It cannot be tested or observed. It cannot be put in a beaker and heated, nor can it be dissolved in a solution and analyzed. The question of God's existence is not a scientific question, it is a philosophical question, and in that realm Mr. Gervais is out of his league. While he is certainly welcome to his opinion, and he is to be admired for his willingness to step into the ring and taking a few swings, he would be well-advised to stick to what he knows. For all his comic genius, Mr. Gervais is a very poor scientist, and an even worse philosopher.