#7. The Lord's Supper is a Seal

Romans 8:16–17 — The Spirit Himself testifies with our spirit that we are children of God, 17 and if children, heirs also, heirs of God and fellow heirs with Christ, if indeed we suffer with Him so that we may also be glorified with Him.

If the Lord's Supper is a sign, it is also a seal to the true believer who partakes in the meal. The seal takes the thing signified and speaks to the believer of his or her personal interest in it.

So, if (as we saw) the Lord's Supper as a sign points to the death of Christ out of infinite love for His people, as a seal it confirms to me that I am one for whom Christ died - that I have an interest in the benefits flowing from His death, because He died for me.

If the Supper as a sign symbolizes believers' participation in and union with the crucified Christ, as they receive and feed upon the bread and the wine, then the Supper as a seal confirms to me personally that I am joined to Christ.
If the Supper as a sign represents to us the fact that our souls are nourished and strengthened by Christ, then the Supper as a seal confirms to me that I am nourished and strengthened by Him.

If the Supper as a sign shows that believers are joined to one another in Christ, then as a seal it confirms to me that I am joined to my Christian brothers and sisters.

In other words, the Supper acts to assure me as a believer of my interest in all the blessings and promises that it signifies.  
Related to this, and building upon it, it is interesting to consider the general functions of a seal in scripture:

• A seal is a mark of ownership. You can tell that something belongs to someone else when it is marked with his seal.  So those who come to the Table are clearly shown to be His people, since this meal is for them and only for them.
• A seal validates a promise. The personal appropriation of the blessings and promises signified in the Table (as we considered above) is an outworking of this.  The Table is one of the places where the Spirit bears witness with our spirits that we are children of God and therefore heirs of all the blessings belonging to His offspring (see our text above).

It is clear from this that those who see the Lord's Supper as simply a memorial really approach it as only a sign and not as a seal.  For them it points to the death of Jesus as a reminder but does no more than that.  The function of the Lord's Table as a means of grace is closely linked to its operation as a seal to the people of God.  This is where the Spirit's influences are felt, and where I am strengthened to live more godly in Christ Jesus.

If we understand this more clearly, it must function as a powerful incentive for us to be present at and to participate in the Lord's Supper, if indeed we are His children, and to marvel again not just that the Son of God entered a sinful world in the likeness of sinful man and was unjustly executed in order to free His people, but more than that - He did it for me!