What is your response to (Leviticus 17:11,14) “for the life of a creature is in the blood” as being a theological basis suggesting that life/personhood begins at implantation when the embryo is infused with blood?
In Hebrew ideology, terms like “flesh” or “skin” (basar) and “blood” (dam) are frequently used to represent all of the physical, biological parts of a body, whether of a human or animal. But the nature of the Hebrew language allows that the same terms have theological implications as well. “Flesh” can be used to speak of the propensity toward sin or to specific sins. The Hebrew word for blood conveys a breadth of meaning which is translated in various passages as “blood,” “bloodguiltiness,” “bloodshed,” “life,” “lifeblood,” and even “death”, so that “blood” also conveys the idea of culpability.
Of the 360 uses of the word dam (blood) in the OT, almost all references can be split into just two categories: there are two references to bloodshed as the result of violence (murder, war, etc.) for every one reference to the sacrificial shedding of blood to God. Blood then becomes an apt metaphor for guilt and death. The blood—always drained out and disposed of on the altar, the ground or elsewhere (Lev 1:5; Deuteronomy 12:24; Exodus 12:7)—represents life which is being offered up in place of actual sin. In making a sin offering to the Lord, the context of passages like Leviticus 3:17 and 17:10-11 is that the offering by fire will expunge the guilt even as the fire consumes all that is on the altar (Leviticus 6:30). No part of the life of sin (represented by the sin offering) is to be withheld for human use or consumption because the toleration of sin, represented by withholding any portion of the offering, always leads to death. This is symbolized vividly when the Lord declares to Moses that any person who eats of the fat or drinks of the blood of the offering is to be “cut off” from among God's people (Leviticus 7:25-27; 17:10-14). To be “cut off” was to be as good as dead as far as the community of faith was concerned.
Some argue that the passage that asserts “the life of the flesh is in the blood” (Leviticus 17:11,14) has implications for ethical dilemmas like the debate over abortifacient “birth control” products. The usual argument is that since blood flow is not established until after nidation—the implantation of the embryo into the lining of the uterus—the death of the embryo does not constitute the death of a person.
This argument represents a self-serving and abusive approach to biblical exegesis since the context of the passages in question all concern sin and the concept of what is due to God in sacrifice. These passages are not attempting to teach a theology of when human life begins and should not be used in support of abortion at any stage.