Don Johnson

If I were doing this debate, here is how I would attempt to do it, take my ideas as suggestions.

1. Establish that in Greek grammatical gender does not imply physical gender. If he does not accept this, then 1 Tim 3:1 proves your case (at least to him) as overseer is feminine grammatical gender.

2. Establish that in Greek is is often possible for a term that refers to males or a male to also refer to a female, this is especially true for plural male forms.

More later.