First, as so many others have pointed out, the Senator mentioned in this piece is a Democrat.
Second, the Republican party is NOT the 'political' wing of the Christian faith (although there are many people on both sides who believe it to be). Yes, Republicans are mostly Christians and Christians are mostly Republicans, but there are many Christians who are Democrats, and most Democrats are Christians. Thus, there are many Christians who are not social conservatives with respect to government; they don't think the government should legislate controversial morality. They recognize the value of Separation of Church and State; they don't want government in religion or vice versa.
As an aside(my objections are now done, wrt your post), this law, if passed, is likely to have very little effect? Aren't many, if not most, online pornography site hosted overseas? Plus, even so, this wouldn't affect online pornography where no money is changing hands, your inbox will still be filled with pornographic spam that links to 'samples'.