If someone is making the claim that there were women priests in the early church, where are they getting this from? Is there any solid evidence for this claim?
If someone is making a claim then the burden of proof is upon them to substantiate the claim. In the case of women’s ordination it was discussed in the early Church because the pagan societies that Christians encountered did have female priestesses. So it would not have been a scandal to those societies if women served as priests. In fact there does seem to be at various points in history certain groups within the Christian community have been confused about whether women could be ordained. However, when the issue was raised the unanimous answer from the Church fathers, Popes and Councils has been in the negative:
We come to the New Testament. If women were ordained to be priests for God, or to do anything canonical in the church, it should rather have been given to Mary in the New Testament… But it was decided differently. She was not even entrusted with baptizing. [after mentioning successions of apostles and priests] but nowhere was a woman established among them. There were four daughters of the evangelist Philip, who were prophetesses, but not priests.
-St. Epiphanius, “Against Heresies” 79 3-4
We have mentioned the deaconesses, who are enrolled in this position, but since they have not received any imposition of hands at all, they are surely to be numbered among the laity.
- Council of Nicea, Canon 19
There is a report that women seem to have been, we know not in what place, admitted to the levitical ministry, contrary to apostolic discipline,and unknown until today …an ordination of this sort must be annulled,and care taken that no one for the future be so bold.
- Council of Nimes, Canon 2
A deaconess does not bless or do any of the things priests and deacons do. She just takes care of the doors and ministers when women are baptized,for the sake of propriety.
- Apostolic Constitutions 8.28.6
The main point of confusion in the early Church appears to have been over the role of Deaconesses. The Church fathers and Councils make clear that the Deaconesses were not ordained and served no clerical function, rather they were appointed to take care of women converts due to social norms of propriety.
There also appear to have been rumors of small groups that thought women could be ordained priests but, once again, the unanimous Church teaching rejected it.
Early Christian heresies or heretical groups cannot be used to guide orthodox theology.