Yes. The Lord's Supper clearly states it is a public proclamation of one's belief in the crucified and risen Lord. It is a public proclamation because the Christian is
active in the Sacrament. "Take eat." "Take drink." In fact, receiving the Lord's Supper is the most public
action we do during the Divine Service. And even through we may not feel or believe that receiving Holy Communion is our testimony of our hope before the world, Scripture
de facto declares it as such.
As a Lutheran, our historic liturgy allows for the congregation to publically testify to their beliefs:
- In unity of our sinful condition and the need of forgiveness of sin--the recitation of the general confession of sins.
- In the unity of belief---the recitation of creed.
- In unity of Christian living---the recitation of the Lord's prayer.
Yet, these liturgical proclamations pale before our grand proclamation---the Lord's Supper.
Your point about John the Baptist and the preaching of repentance is very interesting. The question is raised: Is baptism with repentance a public testimony of our faith the same way as the Lord's Supper?
This question is difficult. Certainly, repentance detached from baptism is not a sacrament and also is not a public testimony of ones faith as no scriptural verse to my knowledge affirms this. So what about original question: Is
baptism with repentance a public testimony of our faith the same way as the Lord's Supper?
And I hope you will be patient and give me more than enough rope to hang myself.
In a word, no. Why? Scripture states no where, baptism with or without repentance is a public proclamation of one's faith. I will grant you repentance
can be a pointer to a public testimony in the same way the recitation of the creed can in a worship service, but it far from being a "stand alone" testimony such as the Lord's Supper.
For if, baptism and repentance is a public testimony we would expect of see it commented in Scripture as such. We would expect those who witnessed baptisms in the NT to comment on the testimonies of the newly baptized, or we would expect the testimonies of those baptized to be recorded in the NT.
Baptism is never spoken of as an event for the eyes of the audience. In most cases, people are baptized as soon as possible, often without audiences as in the Samaritans in Acts 8:12-13, Ethiopian eunuch 8:34-39, Saul of Tarsus 9:17-18, 22:12-16, Cornelius and family 10:14, 44-48, Lydia and family 16:13-15, the Philippian jailer and family 16:30-34, and Crispus and family 18:7-8.