exact iff_mem_imp.mp (membership_iff.mpr $ conj₁'! hpq) hp
case mp
α : Type u_1
inst✝² : DecidableEq α
inst✝¹ : Inhabited α
L : DeductionParameter α
inst✝ : L.Normal
Ω Ω₁ Ω₂ : MCT L
p q : Formula α
hpq : Ω.theory *⊢[L]! p ⟷ q
hp : p ∈ Ω.theory
⊢ q ∈ Ω.theory
no goals