It is common among many religious traditions to offer animal sacrifice or to kill an innocent animal for the perceived wellbeing and longevity of the supplicant.
The innocent victim could be a sheep, a cow or even a poor chicken or rooster. The idea is that innocent animal life is slaughtered to ensure the dispelling of any misfortune from the supplicant and assure the supplicant’s long, prosperous life.
There is a ritual that sums up the reason behind animal sacrifice in few words of prayer. Supplicants swing a live chicken/rooster around their heads three times while saying a prayer that means: “This is my exchange, this is my substitute, this is my expiation. This chicken/rooster shall go to death and I shall proceed to a good, long life and peace.”
The chicken/rooster is then slaughtered and, traditionally, donated to the poor.
But what does the ancient Prophet Zarathushtra say to animal sacrifice???
We read in the poetic gathas, Yasna 32.12:
ýá rávng.hayen srav.ang.há//vahištát šyaöthanát maretánö
aæibyö mazdáv aká mraôt//ýöi géuš möreñden urváḵš-uḵtî jyötüm
ýáiš geréhmá ašát varatá//karapá ḵšathrem.čá îšanãm drûjem.
With their songs of havoc//they avert mortals from best activity/industry,
For them Mazda, the God of creative mind-power/passion has spoken malediction/damnation//Those who murder the living animal with cries of joy,
Instead of willing virtue, excellence//the ritual priests have chosen greed, desiring the kingdom of lies and trick!
We also read in the 3rd rhymed verse line of Yasna 32.14:
hyat.čá gáûš jaidyái mraôî//ýé düraôšem saôčayat avö
When the living animal is spoken for slaughter, they say the dispeller of misfortune/death is lit up in our favor.
To sum it up, Zoroastrianism believes in personal responsibility. No living being carries the sins of others. Animal sacrifice does not wipe out our sins, obligations or responsibilities. It does NOT erase anything but only brings damnation and malediction. It is just a vile carnival of cruelty.
For Zarathushtra, Godhood is virtue, goodness, wisdom and genuine feeling. The best offering to the divine is light, virtue, goodness and genuineness embodied in holy water and wine.
Only demonic deities demand the killing of innocent animal life instead of virtue and light!