My nephew is engaged to a girl whose family has a strong Buddhist faith. Her family want incense to their ancestors burned in the wedding ceremony. The groom's mother is a committed Christian and is refusing her son to be involved in the Buddhist ritual. This refusal has caused great offense to the girl's family, and the wedding may not go ahead. What is the Christian response to this situation?
In your question, you didn’t specify whether the bride and the groom themselves were Christians. If both are Christian, then they should live their lives for Christ witnessing to the truth of the Gospel in everything they do and say, including in how they conduct their wedding ceremony.
In that case, they would be wrong to agree to any ritual or statement contrary to their faith in Christ. Certainly, burning incense to dead ancestors is occult behavior and makes a Christian a sharer in demons, according to 1Corinthians 10:20-21.
On the other hand, if only one member of the couple is Christian (either bride or groom), then the marriage shouldn’t take place at all. The Bible clearly teaches that Christians are only to marry other Christians. To do otherwise leads to an unequal marriage with significant negative consequences, as Paul teaches in 2Corinthians:
2Cor. 6:14 Do not be bound together with unbelievers; for what partnership have righteousness and lawlessness, or what fellowship has light with darkness?
2Cor. 6:15 Or what harmony has Christ with Belial, or what has a believer in common with an unbeliever?
Finally, if neither bride nor groom are believers, then there is no reason to oppose the marriage or insist on any particular wedding style or ritual. While a Buddhist ritual may offend Christian relatives, there is nothing to be gained by stopping it. The two will still be just as unsaved without the Buddhist ritual as with it.
The bigger concern for the Christian family should be the couple's absence of saving faith. Prohibiting a certain wedding ritual will profit no one in eternity. Instead, the Christian family members should place all their time and attention into preaching the Gospel to these young lovers in the hope that they may be saved in the Day of the Lord.