especially if she's devout
I think many factors should be taken into consideration. It goes without saying that a Zevist is way easier to handle as a partner.
Would you prefer a Zevist woman with bad or neutral Planets to you, or a normal person with very good mutual Sinastry (planetary match) for love and relationship? Hard to answer.
If she is devout and active, I see few chances to convert and "restore" her Soul in the short term. So I would discard.
The younger the person is, the easier it is.
If she is simply a brainwashed person, a chance may be given.
Be prepared to face negativity and some reactions by the xian person, until she finally finds the Truth, most likely.
I use to talk by direct experience here. I had partners who were xian at the time, but later on converted to Satan. What I understood is, they are Souls of Satan/Zeus even in past lives and discovering the Truth was on their fate and path, I simply made this process easier with my presence and energy.
I say energy because intermingling with a xian may temporary drag you down or give you a small backlash. This happens because the xian partner is at lower vibrational level in the Soul and has more negative energies involved; when a relationship becomes serious also the energy exchange is serious so, you may be dragged down while she is dragged upwards by you and your energies. So this may require a bit more meditatative effort by your side do "drag her upwards" with you. This happens even if you don't want to, it is simply the effect of a higher and stronger Soul (Zevist) being very close to a standard person. Your partner will be very lucky if you choose this path, because you will wake up and pull upwards a person who probably would not do that alone.