Now that we have explored the sacraments in a general sense, we are prepared to look at each sacrament in more detail. Yet before we do that, we must determine the number of sacraments revealed in Scripture. Christ instituted two sacraments: baptism and the Lord’s Supper (The Heidelberg Catechism, Q&A 68). It is easy to see why the Heidelberg Catechism singles out these ordinances as sacraments. After all, the Gospels reveal explicitly our Savior’s command to baptize disciples and to partake of bread and wine in His memory (Matt. 28:18–20; Luke 22:14–20). Some churches, in addition, have viewed foot washing as a third sacrament. Other churches do not invest foot washing with sacramental significance, although they may have special foot-washing services during the year. Both groups cite John 13:1–20 in defense of the practice. What shall we say about this? Clearly, whatever freedom churches might have to engage in foot washing, no church body may impose it as a sacrament upon its people. First, the early church did not see in John 13 a command for the church in every age to wash feet. Acts, for example, records the disciples administering the sacraments of baptism and the Lord’s Supper (2:37–42), but this New Testament book never records Apostolic foot washing. Second, Dr. R.C. Sproul notes in his commentary John that the majority of the church has not regarded foot washing as a sacrament.
While the above claims are standard Protestant claims, there are some obvious problems with the above claims that we should take a look at. First of all, the use of the terms "sacrament" and "ordinance" are not used in Scripture with regards to Baptism or the Eucharist. So it is somewhat of an "oral tradition" that Protestants are appealing to when they dogmatically apply "sacrament" to these two things. Second, the only time the Bible uses the term "sacrament" in regards to these is when Paul speaks of Marriage as a "great sacrament" in Ephesians 5:32, where the Greek term mysterion ("mystery") which is precisely what the Latin term "sacrament" means (see here). So this is another blatant inconsistency.
Third, the teaching of Jesus to wash the feet of others in John 13:1-20 does sound like something of a sacrament, especially in 13-14, where Jesus says: "If I, your Lord and Teacher, have washed your feet, you also ought to wash one another's feet. For I have given you an example, that you also should do just as I have done to you." This is an outward ordinance or ritual, that Jesus expressly commands, and is clearly tied to being washed of sins and being part of the community (v8): "If I do not wash you, you have no share with me." This line of Jesus is especially noteworthy, because while Peter was already a believer in Jesus, here we see Jesus tell Peter that if Peter refuses to have his feet washed, then Jesus will disown Peter. This passage not only poses a problem for 'once saved always saved' but it also exposes the Protestant bias and inconsistency in their theology. And even if it is not a sacrament, the Church has historically seen it as an official part of the Liturgy, particularly on Holy Thursday, also called "Mandate Thursday" in Latin because Jesus "mandates" (commands) the washing of feet. So this is not "optional" for the Protestant side, yet most Protestants do not even practice the foot washing rite in any formal/concrete manner.
