When he says "About a third of Bush supporters say they never go to church", that's incorrect. What the 2 columns marked "Bush Voters" and "Kerry Voters" show are the division in that category between the Bush and Kerry voters - ie of the American voters who never go to church, 34% voted for Bush, while 64% voted for Kerry. Check, and you'll see the pair of figures always add up to about 100%.
This is clearer (and you get the full information you need) if you look at the polling firm's web page:
http://www.populuslimited.com/ . For instance, that says 15% of voters never go to church; therefore, .34 * 15% = 5.1% of all voters are non-churchgoing Republicans (or 5.1% / 0.51 = 10% of Bush voters never go to church, since Bush got 51% of the countrywide vote).
So, assuming the voting figure to be 51% Bush, 48% Kerry, here are the real American figures, which can then be compared with the British ones:
Church going Bush Kerry
more than weekly 20 12
weekly 30 22
monthly 14 15
few times a year 24 30
never 10 20
Abortion
always legal 10 32
mostly legal 25 44
mostly illegal 37 15
always illegal 23 7
Gay marriage
Marry 11 42
civil union 35 35
no recognition 49 23
This shows that, for instance, Tory voters are slightly more in favour of gay marriage than Republicans (their split was 18:39:39), in direct contradiction to what the article says.
Also: no-one in Britain goes to church anywhere near as much as Democrats, let alone the Republicans; the Tory attitude to abortion roughly matches that of Kerry voters; it's only 23% of Republicans who want abortion banned in all circumstances (though the 37% saying it should be "mostly illegal" may just be thinking of when the woman's like would be at serious risk, of course). And only 7% of Kerry voters think abortion should always be illegal, not the 'fifth' given in the article.