Thanks for your note and question. First, I’ll give you the answer to your first question from the article on “Sacraments” in the New Bible Dictionary:
SACRAMENTS. The word ‘sacrament’ (Lat. sacramentum) in its technical theological sense, when used to describe certain rites of the Christian faith, belongs to the period of the elaboration of doctrine much later than the NT. The Vulgate in some places thus renders Gk. mysteµrion (Eph. 5:32; Col. 1:27; 1 Tim. 3:16; Rev. 1:20; 17:7), which was, however, more commonly rendered mysterium (*Mystery). In early ecclesiastical usage sacramentum was used in a wide sense of any ritual observance or sacred thing.
In everyday usage the word had been applied in two ways: (1) as a pledge or security deposited in public keeping by the parties in a lawsuit and forfeited to a sacred purpose; (2) as the oath taken by a Roman soldier to the emperor, and thence to any oath. These ideas later combined to produce the concept of a sacred rite which was a pledge or token, the receipt of which involved an oath of loyalty, and this led in time to the limitation of the word ‘sacrament’ to the two major rites of divine institution, Baptism and the Lord’s Supper. The wider use continued for many centuries. Hugo of St Victor (12th century) can speak of as many as thirty sacraments, but Peter Lombard in the same period estimated seven as the number. The latter estimation is officially accepted by the Roman Church.
The common definition of a sacrament accepted by the Reformed and Roman Churches is that of an outward and visible sign, ordained by Christ, setting forth and pledging an inward and spiritual blessing. The definition owes much to the teaching and language of Augustine, who wrote of the visible form which bore some likeness to the thing invisible. When to this ‘element’, or visible form, the word of Christ’s institution was added, a sacrament was made, so that the sacrament could be spoken of as ‘the visible word’ (see Augustine, Tracts on the Gospel of John 80; Epistles 98; Contra Faustum 19. 16; Sermons 272).
Does the NT teach the obligation of sacramental rites on all Christians? What spiritual benefit is there in their reception, and how is it conveyed?
The obligation to continue sacramental rites depends on: (1) their institution by Christ; (2) his express command for their continuance; (3) their essential use as symbols of divine acts integral to the gospel revelation. There are only two rites obligatory in these ways on all Christians. There is no scriptural warrant for giving the other so-called sacramental rites (i.e. Confirmation, Orders, Matrimony, Penance, Extreme Unction) the same status as *Baptism and the *Lord’s Supper, which from the beginning are together associated with the proclamation of the gospel and the life of the church (Acts 2:41-42; cf. 1 Cor. 10:1-4). They are linked with circumcision and the Passover, the obligatory rites of the OT (Col. 2:11; 1 Cor. 5:7; 11:26). The Christian life is associated in its beginning and in its continuance with sacramental observance (Acts 2:38; 1 Cor. 11:26). Some of the deepest lessons of holiness and perfection are implicit in what Scripture says regarding the Christian’s sacramental obligations (Rom. 6:1-3; 1 Cor. 12:13; Eph. 4:5). References to the sacraments may underlie many passages where there is no explicit mention of them (e.g. Jn. 3; 6; 19:34; Heb. 10:22). The risen Lord’s great commission to the disciples to go to all nations with the gospel specifically commands the administration of Baptism and clearly implies observance of the Lord’s Supper (Mt. 28:19-20). Christ promises to be with his servants until the end of time. The work to which he has called them, including the observance of the sacraments, will not be completed before then. Paul also has no doubt that the Lord’s Supper is to be continued, as a showing forth of the death of Christ, till he comes again (1 Cor. 11:26). It is true that Matthew and Mark do not record the command ‘this do in remembrance of me’, but the evidence of the practice of the early church (Acts 2:42; 20:7; 1 Cor. 10:16; 11:26) more than compensates for this.
The efficacy of the sacraments depends on the institution and command of Christ. The elements in themselves have no power; it is their faithful use that matters. For through them men are brought into communion with Christ in his death and resurrection (Rom. 6:3; 1 Cor. 10:16). Forgiveness (Acts 2:38), cleansing (Acts 22:16; cf. Eph. 5:26) and spiritual quickening (Col. 2:12) are associated with baptism. Participation in the body and blood of Christ is realized through Holy Communion (1 Cor. 10:16; 11:27). Baptism and the cup are linked together in the teaching of our Lord when he speaks of his death, and in the mind of the church when it remembers its solemn obligations (Mk. 10:38-39; 1 Cor. 10:1-5).
The sacraments are covenant rites: ‘This cup is the new covenant’ (Lk. 22:20; 1 Cor. 11:25). We are baptized ‘into the name’ (Mt. 28:19, rv). The new covenant was initiated by the sacrifice of the death of Christ (cf. Ex. 24:8; Je. 31:31-32). Its blessings are conveyed by God through his word and promise in the gospel and its sacraments. There is clear evidence that many in apostolic days received blessing through the administration of the sacraments accompanied by the preaching of the word (Acts 2:38ff.). It was the gospel word or promise accompanying administration which gave meaning and efficacy to the rite. Those who had received only John’s baptism were baptized again ‘in the name of the Lord Jesus’ (Acts 19:1-7). It is apparent also that some received the sacraments without spiritual benefit (Acts 8:12, 21; 1 Cor. 11:27; 10:5-12). In the case of Cornelius and his household (Acts 10:44-48) we have an example of some who received the gifts which baptism seals, before they received the sacrament. Nevertheless, they still received the sacrament as bestowing benefit and as an obligation.
In the NT there is no conflict suggested between the use of sacraments and spirituality. When they are rightly received the sacraments do convey blessings to the believer. But these blessings are not confined to the use of the sacraments, nor when they are conveyed through the sacraments does their bestowal conflict in any way with the strong, scriptural emphasis on faith and godliness. The sacraments, when administered in accordance with the principles laid down in Scripture, recall us continually to the great ground of our salvation, Christ in his death and resurrection, and remind us of the obligations we have to walk worthily of the calling wherewith we are called.
Bibliography. O. C. Quick, The Christian Sacraments, 1932; G. Bornkamm in TDNT 4, pp. 826f.; J. Jeremias, The Eucharistic Words of Jesus, 1955; W. F. Flemington, The New Testament Doctrine of Baptism, 1957; A. M. Stibbs, Sacrament, Sacrifice and Eucharist, 1961; G. R. Beasley-Murray, Baptism in the New Testament, 1962; J. I. Packer (ed.), Eucharistic Sacrifice, 1962; D. Cairns, In Remembrance of Me, 1967. r.j.c.
As to your second question. I think that there is a difference between foot washing and a sacrament. Jesus was trying to teach His disciples the need for humility and servanthood when He washed their feet. This He did as an example. Jesus said, "I gave you and example that you also should do AS I did to you"(John 13:15). There is, I believe, a significant difference between doing "what" Jesus did and doing something "as" Jesus did. Jesus was serving His disciples out of humility; they should likewise serve each other out of humility. Their humble service was not to be restricted to foot washing. But when Jesus instituted the Lord’s Supper (Communion) He said, "This do in remembrance of Me" (Luke 22:19).
We never see foot washing being practiced by the apostles or anyone else in the Book of Acts or the rest of the New Testament, but we do read that they constantly met together to "break bread" in remembrance of our Lord (Acts 2:42; 20:7; 1 Corinthians 11:17-34).
I don’t fault those who wish to wash the feet of their brethren, but I do think that we should see this as a symbolic act, which has many other applications.