Why are Christians so against abortion?

With the Conservative government in Canada taking a stronger stance against abortion and with the massive pro-life rally in Ottawa today it seems like a good time to touch upon this issue. More to the point, my specific question is "Why is abortion such a huge issue when it comes to elections?"
One of my friends recently expressed his opinion that abortion should not be such a big deal for believers. He suggested that there are other issues to be concerned about in elections. There most certainly are other important issues when it comes to the polls, however, no issue in Canada holds the same urgency and weight as abortion does.
My personal thinking on the subject goes along these lines. If I were living in a country where the current government was engaged in or was permitting the extermination of one group of people, and if this country held regular elections, I would consider it my duty to vote against that government. It would not matter whether the future potential government held the same social agendas as I do or whether they could help the country financially - heck, it wouldn't even matter if this other political party were completely inept. All that would matter to me is seeing the end of this genocide.
For Christians, the slaughter of a specific segment of the human race is taking place with government approval and government funding. Christians have no choice but to stand up for the unborn with their vote. You may disagree with us that the unborn are fully human, but if you enter into our mindset, you should be able to understand our reason for taking abortion so seriously.

I know she found peace

Very close to our church there is a brothel. One of our workers has spent significant time chatting with some of the women there. Several days ago she shared a story of sadness and hopelessness. One of the prostitutes whose husband is handicapped has left her homeland, burdening her eldest child with the responsibility of caring for her other children. This eldest child has begun to question her mother's love: "How can you love me if you leave me like this?"
What a picture of sadness! Sadness on the part of the family which has lost its mother. Sadness on the part of the husband who is unable to provide for his family and knows that his wife is in the sex trade. Sadness on the part of the woman who has left those she cares most about, lives in a foreign land and engages in a dehumanizing profession.
However, in the midst of this, there is a ray of hope. Amazingly, several weeks ago, the lady who ran the brothel became a Christian. This worker from our church and her friend shared the story of the Gospel and its message of hope led to new life. The Gospel still has power to bring about restoration today! May more and more broken people hear this news and be lifted out of their pain and hopelessness.