You mean the highest % of religious? See chart here , by God's grace.
As to your second query, which perhaps is why the court does not look like America,
Chief Justice John G. Roberts, Jr..................................Roman Catholic
Justice Antonin Scalia................................................Roman Catholic
Justice Anthony Kennedy............................................Roman Catholic
Justice Clarence Thomas............................................Roman Catholic
Justice Ruth Bader Ginsburg.......................................Jewish
Justice Stephen Breyer...............................................Jewish
Justice Samuel Alito..................................................Roman Catholic
Justice Sonia Sotomayor............................................Roman Catholic
Justice Elena Kagan...................................................Jewish
http://wiki.answers.com/Q/What_is_the_religion_of_each_US_Supreme_Court_Justice
At least there are more conservative Catholics than liberals ones on it, and Prot mainliners (John Paul Stevens) are more like liberal Catholicism.
Yet i suppose it is unlikely a Scalia would be found today as a high level judge , and likely wise Prot, evangelicals, as they are too conservative. .
Also, evangelicals tend to be less educated as regards going thru the kind of educational ranks needed in order to rise far in the promotion process
While there has been a great increase in Christian college enrollment, few are going to go to Harvard Law School (as Roberts, Scalia, Kennedy, Breyer, Kagan) or Yale Law School (Thomas, Sotomayor).
In addition, evangelicals are very underrepresented in national politics, from whence cometh the high level nominations or appointments.
But it is still government by the people, who elect the members of government, and the liberal nature of it is a judgment upon this country, and which tests the faithful.
They have set up kings, but not by me: they have made princes, and I knew it not: of their silver and their gold have they made them idols, that they may be cut off. (Hosea 8:4)
Meanwhile, consistent with secular colleges,
91% of faculty and administrators from Americas top 23 Catholic universities who contributed to presidential campaigns in 2012 gave to President Obama. 89.6% of all 928 donors contributed to Obama, versus 10.3% who gave to Romney. Based on official Federal Election Commission data made available by OpenSecrets.org; http://www.campusreform.org/blog/?ID=4529
As a white Protestant early 18th century American (United Methodist) I have nothing against other cultural or religious beliefs, but as a USA majority demographic I definitely do not want ruled by them.
I want my cultural beliefs represented at the table of justice and in Congress and in Cabinet positions and at the Ivy League universities where the candidate pool for these high level positions originates.
Perhaps more of us need to demand a seat at the table instead of being forced to ride at the back of the bus.