Q. 162. What is a sacrament?
A. A sacrament is an holy ordinance instituted by Christ in his church, to signify, seal, and exhibit unto those that are within the covenant of grace, the benefits of his mediation; to strengthen and increase their faith, and all other graces; to oblige them to obedience; to testify and cherish their love and communion one with another; and to distinguish them from those that are without.
According to the Westminster Larger Catechism (Q&A 161), the sacraments are more than signs. Through the sacraments, when received by faith, believers faith are strengthen, nourished, increased, and the like.
We must also concede the mysterious nature of the sacrament and how the Holy Spirit chooses to work through them, to the benefit of believers.
But I refuse to believe that they are merely symbolic. In fact, it was one of the things that I struggle with as a Baptist.