Unless you're God, in which case life can be discarded based on your mood at the moment.
I don't think of God as moody, can you be more specific?
If murder is nothing more than "a killing I have judged as Unjust", then every killing is murder, because you can always find someone who thinks it was Unjust.
The bible does NOT list abortion as unjust, and even suggests it is the opposite in some cases; in others, it charges a fine against the one who caused the spontaneous abortion (rather than accusing them of murder).
The Christian understanding of whether abortion is murder or not is far from cut-and-dry...
In the Christian worldview murder is synonymous with hatred for your fellow man let alone all the actions that flow from that that result in a death.
At the risk of being redundant something I believe worth emphasizing is paradigm. Standard according to whom or what and perhaps the definitions being utilized by representing that standard. A clear cut example would be today's partial and sporadic legalization of marijuana throughout the same region or country. Depending on jurisdiction one is either inside or outside of the law for the exact same details. This is how it is with abortion, people can appeal to a specific standard and that would result in a different understanding.
I bring this to your attention because you have alleged that anyone can merely claim a killing is unjust to be considered murder.
In order for a killing to be considered murder in the biblical sense, there are three requirements: First, the killing must be intentional; second, it must be a human that is killed; and third, the killing must be unlawful or unjust.
It would seem with pointvthree that you may have some traction, but in the end what is unjust is defined by scripture.
There are a limited number of situations in which the Bible considers even the killing of another human not to be a sin. The first of these is the case of capital punishment. In several portions of the Old Testament law, God specifically commands that the leaders of Israel put people to death for certain crimes, such as murder or treason.
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The second of these cases is that of a true accident, where the murder did not occur intentionally, but was the result of a mistake on the part of the killer and was not intended to cause death.
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The third case is that of self-defense. The Bible never condemns a person for killing another as a result of defending himself or his family from a robber, intruder, or another who is seeking to harm them.
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The last circumstance in which killing is not considered murder by the Bible is the case of a soldier killing in war.
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Under these limited circumstances, a killing would not be considered murder from a moral perspective, but otherwise, the Bible considers all instances of one human directly causing the death of another to be murder. In fact, the Bible even considered the person who desires to murder another person to be guilty of murder in God’s eyes. (1 John 3:15)
Nic