Note : In 1981, chapters 56, 57 and 58 were given constitutional status
[cf. M8GA (1980), III, Item 9, p. 118 and M9GA (1981), 9-65, Item 6, p. 137]

58-2. The ignorant and scandalous are not to be admitted to the Lord’s Supper.

DIGEST : The text of the current BCO 58-2, though not in the exact wording, goes back to the 1645 Directory for the Publick Worship of God, and the same intent was found as part of the PCUSA and PCUS Directories for Worship up through 1927 for the PCUS. Because the section had been deleted, presumably in 1929, and so was not found in PCUS 1933, it did not find its way into either the Proposed BCO (1973) or the first approved PCA BCO (1973). Thus the inclusion of this section in 1975 was effectively a re-inclusion of the text [cf. M3GA, 3-89, p. 97], indicating that the Committee for Constitutional Business had researched the matter and looked back behind PCUS 1933 in bringing forward its recommendations.

BCO 58-2 is basically a shortened form of the answer to the Westminster Larger Catechism's Question 173:
Q. 173. May any who profess the faith, and desire to come to the Lord's supper, be kept from it?
A. Such as are found to be ignorant or scandalous, notwithstanding their profession of the faith, and desire to come to the Lord's supper, may and ought to be kept from that sacrament, by the power which Christ hath left in his church,[1 Cor. 11:27-34; Mt. 7:6; 1 Cor. 5; 1 Tim. 5:22] until they receive instruction, and manifest their reformation. [2 Cor. 2:7]

BACKGROUND AND COMPARISONS :
1. PCA 1973, DfW, Adopted text, as printed in the Minutes of General Assembly
2. Continuing Presbyterian Church 1973, DfW, Proposed text
[no comparable text]

1. PCUS 1927, DfW, XI-2, § 348
2. PCUS 1894, DfW, XI-2
3. PCUSA 1797, DfW, VIII-2
The ignorant and scandalous are not to be admitted to the Lord's supper.

The Directory for the Publick Worship of God (1645), "Of the Celebration of the Communion"
"The ignorant and the scandalous are not fit to receive the sacrament of the Lord's Supper."

COMMENTARY:
Morton H. Smith, Commentary on the Book of Church Order, 6th edition, 2007, p. 439
Here is a clear statement as to those not admitted to the Table. First, those who do not know the Gospel, and have not received Christ cannot be admitted to the Table. Those, who cannot understand the nature and meaning of the Sacrament should also be excluded. The second group are the scandalous. These are, no doubt, persons who have professed Christ as Savior, but who have strayed into scandalous sins. These are to be barred from the Table.