Written by Water mattered in Zoroastrian ritual long before Christianity existed. That is true. The harder question is whether Christian baptism came from a specific Zoroastrian rite.
Start with what the Zoroastrian evidence actually says
Zoroastrian ritual life gives cleansing a serious place. Encyclopaedia Iranica documents ordinary washing, the pādyāb-kustī complex, and the much more elaborate barašnom purification rite. These practices belong to a larger system concerned with purity, pollution, preparation for worship, and protection of the good creation.
The barašnom is not simply an ancient baptism. It is a specialized purification procedure with several cleansing agents and, in its full form, a period of seclusion. Calling the two rites identical would erase the very differences we are trying to understand.
Judaism already had a water world of its own
Jewish scripture and Second Temple practice contain extensive washing and immersion traditions. By the time John the Baptist appears, ritual immersion is already part of the Jewish religious environment.
John still did something distinctive with it. His baptism was tied to repentance and to the movement gathered around him, and the Jesus movement inherited baptism from that immediate Baptist setting. That makes a simple line from Zoroastrian purification to Christian baptism difficult to prove.
Could Iranian purity ideas have formed part of the wider world in which Jewish ritual developed? Yes. Iranian and Jewish communities had centuries of contact, and both traditions built elaborate systems around purity and moral order. But shared use of water is not enough. Water purification is everywhere.
Where the comparison gets stronger
There is a useful control case in Islam. Iranica’s discussion of Zoroastrian cleansing treats the resemblance between the pādyāb ablution before five daily prayers and Islamic wuḍūʾ before five daily prayers as so close that Zoroastrian influence is described there as virtually certain.
That is exactly why we should not grade every comparison the same way. One ritual connection can be strong while another remains open.
For Christian baptism, the missing piece is still the bridge. We would need evidence connecting a particular Iranian rite to Jewish immersion or directly to the Baptist movement, not just priority and resemblance. Until that turns up, the honest conclusion is simple: the comparison is real, the contact is historically possible, and the direct genealogy is not proved.