Dear Anonymous,

Thanks for the question.

You said:
I recently attended a Catholic wedding. During the sermon, the priest said something to the effect that performing a ritual makes the act behind it true.

• Where is that in The Bible?

You are not going to find it in the Bible because the priest is addressing the theology behind the sacraments of the Church and the Bible has nothing to do with the sacramental theology of the Church.

What he said was correct. Matrimony is a sacrament and like all sacraments, they are outward signs instituted by Christ that give sacramental grace. All sacraments require a certain form (words), matter, and a proper intent. When any validly ordained priest administers any of the seven sacraments, Jesus is using the body of the priest to administer the sacrament. Jesus instituted seven sacramental rituals or ceremonies. These are continued on by His Church:

1. Baptism
   
2. the Eucharist
   
3. Confirmation
   
4. Confession
   
5. the Anointing of the Sick
   
6. Matrimony, and
   
7. Holy Orders, the sacrament that makes a man a priest.
   

The word sacrament comes from a word meaning to swear a covenant oath, meaning the person receiving the sacrament is promising to:

• do the best they can to receive the sacrament properly and
• obey what is required by any sacrament

and God Himself is promising to stand by what sacramental grace is conferred on the receiver(s).

This posting addresses where the sacraments are in the Bible:

• Are there Biblical quotes that substantiate that Jesus instituted the sacrament of Matrimony?
  

I hope this helps,

Mike