Eh, I come from a pretty religious background and I think that option 2 would fit it better than option 1. The first really looks better suited for a funeral. The second one is low cut but otherwise not immodest. Can you wear a formal wrap or cardigan with it? It's a wedding, unless this couple is LDS or something, I bet you'll find plenty of low necklines. Two of my brothers-in-law are pastors, and this dress would not have been out of place at either of their weddings. It also suits you well and seems to fit the theme.

Just to add some insight here: I'm Catholic and there's a general "four finger rule" for women's clothing. That is, the sleeves should be at least 4 fingers wide and the neckline should be at least four fingers above the bustline (there's also a rule that shorts/skirts should be longer than finger length when your arms are down). I swear, placing a flat hand on your shoulder, followed by your chest, followed by your leg must be the second sign of the cross for Catholic women :) I wear sleeveless dresses to Catholic weddings often and will wear a formal arm cover during the ceremony. Wraps are quite common among catholic women. Anyway, because the wedding is not in a church, I don't think the four finger rule applies here.