Some months ago, I finished reading Embryo: A Defense of Human Life, put out by Princeton University's Robert P. George and the University of South Carolina's Christopher Tollefsen:
The book is thorough, airtight, and painstakingly researched in its presentation of the facts that human embryos, considered mere "balls of cells" or "potential human beings" by many people, are, in fact, "actual human beings with potential."
Those who support the destruction of human embryos -- specifically, for the purposes of stem-cell research -- have persistently argued that those who describe embryos as human beings are merely foisting their religious ideology or personal views on the rest of the populace, but George and Tollefsen make little to no reference to God or any sort of religion or religious belief throughout their work, instead presenting the facts of embryology (citing numerous embryology texts already in existence) and carefully picking apart the various arguments that have been put forth over the years by the pro-ESCR lobby. As someone who makes no claims of having inside information on what or who created us, I can tell you that the authors' arguments will convince the most confident atheist as well as the most devout believer. Further arguments are made as to what should be done with those human embryos currently trapped in a cryogenic limbo in fertility clinics.
Embryo is a good resource for those who'd like some more scientific substance in their defense of human embryos, and might give those who support embryonic research a little something to think about -- namely, that most of the people who oppose it really aren't anti-cure Luddites who wish to see more people suffering and dying from disease.