7; and _De unitate ecclesiae_,
6: "habere non potest Deum patrem qui ecclesiam non habet matrem"). The
Church thus became the sole ark of salvation, outside of which no one
could be saved.

Intimately connected with the idea of the Church as an ark of salvation
are the sacraments or means of grace. Already as early as the 2nd
century the rite of baptism had come to be thought of as the sacrament
of regeneration, by means of which a new divine nature is born within a
man (cf. Irenaeus, _Adv. Haer._ i. 21, 1, iii. 17, 1; and his newly
discovered _Demonstration of the Apostolic Teaching_, chap. 3), and the
eucharist as the sacrament of the body and blood of Christ, feeding upon
which one is endowed with immortality (cf. Irenaeus, _Adv. Haer._ iv.
18, 5, v. 2, 2). In the early days the Church was thought of as a
community of saints, all of whose members were holy, and as a
consequence discipline was strict, and offenders excluded from the
Church were commonly not readmitted to membership but left to the mercy
of God. The idea thus became general that baptism, which had been almost
from the beginning the rite of entrance into the Church, and which was
regarded as securing the forgiveness of all pre-baptismal sins, should
be given but once to any individual. Meanwhile, however, discipline grew
less strict (cf. the _Shepherd of Hermas_, Vis. v. 3; M. iv. 7; Sim.
viii. 6, ix. 19, 26, &c.); until finally, under the influence of the
idea of the Church as the sole ark of salvation, it became the custom to
readmit all penitent offenders on condition that they did adequate
penance. Thus there grew up the sacrament of penance, which secured for
those already baptized the forgiveness of post-baptismal sins. This
sacrament, unlike baptism, might be continually repeated (see PENANCE).
In connexion with the sacraments grew up also the theory of clerical
sacerdotalism. Ignatius had denied the validity of a eucharist
administered independently of the bishop, and the principle finally
established itself that the sacraments, with an exception in cases of
emergency in favour of baptism, could be performed only by men regularly
ordained and so endowed with the requisite divine grace for their due
administration (cf. Tertullian, _De Exhort. cast. 7; De Bapt. 7, 17; De
Praescriptione Haer. 41_; and Cyprian, _Ep. 67._ For the later influence
of the Donatist controversy upon the sacramental development see
DONATISTS). Thus the clergy as distingui