Well, I can believe it. I have two good friends who are extremely intelligent, very worldly, and knowledgeable about the issues. They are also extremely devout and refuse to vote for a pro-choice candidate. Between half a million and a million abortions occur every year in the United States. If you believe each of those represents a homicide, I can see why the issue would be compelling.
EDIT: This Wikipedia article
http://en.wikipedia.org/wiki/Abortion_in_the_United_States#Public_Opinion gives a poll on public opinion conducted in 2003. Here's the crosstab:
Group | Generally available | Available, but with stricter limits than now | Not permitted |
Overall | 39% | 38% | 22% |
Women | 37% | 37% | 24% |
Men | 40% | 40% | 20% |
Democrats | 43% | 35% | 21% |
Republicans | 29% | 41% | 28% |
Independents | 42% | 38% | 18% |
Northeasterners | 48% | 31% | 19% |
Midwesterners | 34% | 40% | 25% |
Southerners | 33% | 41% | 25% |
Westerners | 43% | 40% | 16% |