In "Aphrodite to Zeus: An Encyclopedia of Greek and Roman Mythology" by Luke Roman and Monica Roman one can find the following notation regarding Iphigenia.
Iphigenia. Daughter of Agamemnon and Clytaemnestra. Iphigenia appears in Euripedes' Iphigenia at Aulis and Iphigenia Among the Taurians. Additional classical sources are Apollodorus's Library (Epitome 2.10, 3.21-22), Homer's Iliad (9.145, Hyginus's Fabulae (98, 120, 122), Ovid's Metamorphoses (12.23-38, 13.182-195), and Pausanias' Description of Greece (1.33.1, 2.22.6-7, 9.19.6-7). When Agamemnon and the Greek fleet were trapped by unfavorable winds at Aulis, Calehas prophesied that he must sacrifice his own daughter to gain fair winds for sailing. Artemis, angry at Agamemnon for killing a deer or a sacred goat, or for failing to fulfill a vow, or for boasting of his superiority in hunting, demanded the sacrifice. In Euripides' Iphigenia at Aulis, Agamemnon sends for Iphigenia on the pretext of marriage to Achilles, but in this play, as in other versions, Artemis replaces her with a deer in the moment before she is killed. Aeschylus's Agamemnon seems to imply that she was actually killed, although Aeschylus may have been aware of the story of her replacement.... For the Roman poet Lucretius, Iphigenia's sacrifice is a grim example of the destructive nature of superstition."
Compare this story with the story of Abraham and Isaac in Genesis 22:1-12.
ISAAC, the son of Abraham, Whereas Iphigenia was considered important enough to propitiate the angry winds of God which threatened the life of Agamemnon, by sharp contrast, the only thing we can see in Isaac to merit sacrifice is his complete anathema to Hagar, the preferred, younger and more beautiful mistress to Abraham. When Isaac was born to Abraham's much older wife, Sarah, Sarah insisted that Abraham deport Hagar and her son which Abraham did. It is very likely that when Hagar got her advantage over Abraham she demanded the same of Sarah's son, Isaac.
The story comes down to us from the Bible in the form of God himself commanding Abraham to sacrifice his second son, Isaac which Isaac starts to do but in the moment that he is about to slit his son's throat an angel appears with a lamb which he tells Abraham to sacrifice instead. The angel was undoubtedly a voice in Abraham's head that contradicted the previous voice in Abraham's head that told him to sacrifice Isaac.
THE MOST BELOVED CHILD OF ONE MAN IS THE MOST HATED OF ANOTHER.
In war, it is common that the conqueror will kill the children of the conquered to prevent the conquered to rise up against the conqueror in the next generation. Another way of dealing with the children of the conquered is to train them in the ways of the conqueror and use them as liasons to promote the culture of the conquered to the lands of conquest. Cesear Augustus took the children of nobles from Germania to Rome to make them into Romans. Julius Ceasar impregnated Cleopatra to create a Roman heir to the Egyptian throne. It is likely that Cesar Augustus impregnated Mary to create a Roman King to rule over the Israelites.
Child sacrifice is a boon to whoever does not want the child and a threat to whoever wants the child. In today's world women have flocked to abortionists to free them from the burden of caring for unwanted children. This is seen as child sacrifice to the men who want the children to be born.