Do Christians have to get married in a church building?

Thanks for your question. It is great that both you and your wife to be are Christians. As you know, God sets the parameters of marriage. He says for us not to be unequally yoked together (2 Cor. 6:14) and that we should be married only in the Lord (1 Cor. 7:39). So-called Christian marriages that are otherwise can end in disaster (i.e. Ahab and Jezebel, 1 Kings 16:31).

While there is no Scripture reference that states we must have a wedding at a particular location; we should always strive to show prudence in all things. A building does matter as they are a form of communication too. Some questions I would ask myself:

(1) If you could marry someone at the Kingdom Hall of the Jehovah's Witnesses, a Muslim Mosque, or Mormon Temple what would this communicate to others that attend or that read about your marriage? While the building may be "free" financially, its "cost" may be substantial to your Christian witness in the community.

(2) What is the motivation of the JW's offer? Is there a JW family member involved in the decision?

(3) Where do you and your wife to be go to church presently? Will your pastor do a marriage ceremony outside his own church walls? Is there a friend that owns a nice location for a possible marriage - a beautiful garden, lake scene, etc.?

Marriage is ordained by God as a covenant relationship before Him (Gen. 2:24). Moreover, as Christians, we should desire that every aspect of our lives - including our marriage - to glorify God (1 Cor. 10:31). So, a Christian marriage should be Christ-centered. As such, I would counsel anyone desiring to be married not to do so in a building used for cultic purposes. This said, some may desire to use such a circumstance as a mission opportunity (cf. Acts 17:16-34, but note that Paul wasn't getting married, was provoked in his spirit to deal with idolatry [Acts 17:16], some of the people were willing to hear [Acts 17:20], and Paul was theologically prepared for such [Acts 17:22-31]).

Note: A couple that was married at a location similar to the three mentioned above before their conversion to Christ, should not feel condemned for such as they weren't saved at the time. I would use such a circumstance for a testimony to the Lord; I once was lost but now I'm saved.