Still, they make some interesting observations. I don't think I'm misrepresenting them when I pull out this as representative of their insights:
Now you could almost certainly say the same thing about who wins on just about any left-right axis you choose, say for example butter vs. guns or individual liberty and privacy vs. national security. But this version of the axis has been at the fore because most of us attribute some of the most grotesque recent episodes in our politics -- such as the Bush administration undercutting scientific research and the insistence on sticking tubes into the inert Terry Schiavo -- to the religious version of the axis.
Domke and Coe show that politicians use the tactic of "narrowcasting" to walk the tightrope between showing allegiance to religious concerns and scaring off moderates and the secular fraction of the population. That is, they send signals to conservative religious people that are invisible or little noticed by others, such as visiting evangelical colleges or declaring "a day of prayer."
I do have to say that I, and probably millions like me who value a religious faith, resent being verbally linked to folks whose faith requires such secret signals from political actors. But that's another problem.
The Domke-Coe book came out before the 2008 cycle. I'm sure they'd observe that the Obama campaign largely followed their golden rule for attracting conservative Christians without scaring off others, even though Obama improved his fraction of the white evangelical vote only marginally, if at all, over Kerry in 2004.
I think it is worth considering whether perhaps contemporary intense, engaged political chatter on the internet is reducing the value of narrowcasting. It used to be that politicians could dog-whistle their more controversial constituencies with relative impunity: the mainstream was never going to know (or at least report) they'd been signaling to the fringes. No more. Rightwing theocrats instantly call out the slightest deviations from their guys on their core issues like abortion and gay rights while the left blogosphere howls as when Democrats make conciliatory gestures to Christianists such as Obama fronting the homophobic singer-preacher Donnie McClurkin in southern primaries. (The Rick Warren episode at the inauguration was something else, not narrowcasting, but in all probability a serious instance of tone-deafness.) On both ends of the spectrum, channels between activists and more mainstream media outlets are opening up; what was hidden is more frequently spotlighted.
Domke and Coe's "God Strategy" can't operate underground any more. Their book is successfully descriptive of an era, but an era that I think, and hope, is coming to an end. Politicians and religious constituencies are being forced to be more honest with the nation at large. This should lead to debate over the ground level policy implications of what were just throw-away cues to niche constituencies. That has to be good -- such policy debate is the ground on which a multi-faith, legally secular democracy should make choices.