Des Moines — Jenifer Bowen, the executive director of Iowa Right to Life, spent a recent evening at the Hoyt Sherman Place theater here listening to four Republican presidential candidates deliver faith-infused pitches to about 1,000 evangelicals representing one of this election’s most critical and conflicted voting blocs.

In 2008, evangelical support washed over former Arkansas governor and Southern Baptist preacher Mike Huckabee, but this year Bowen expressed bewilderment at the theological and electoral calculations that were leading conservative-values voters to bestow their blessing on one candidate after another.