There are a lot of evangelicals in iowa who skew the gop vote. They are certainly not Trump's crowd, and the reason that huckabee and santorum, two christian oddballs, did well in iowa in years past. The gop primary/caucus process is basically about appealing to wingnuts and christians, which is pretty why the republicans have been losing ground nationally (except in the deep south, of course--which has plenty of both!). New Hampshire is different, so that will be an interesting contest. Trump will have to win NH, or his balloon will quickly deflate and his candidacy will probably be over and it will be a contest between cruz (texas wacky) and rubio. Then it's on to extremely conservative South Carolina, where the christians will again be out in force.