Before attempting to understand the significance of the variations one must begin with a more accurate table and an understanding of the Greek grammar.
| Verse |
Greek |
Transliteration |
KJV |
| Acts 2:20 |
τὴν ἡμέραν κυρίου |
tēn hēmeran kyriou |
the day of the Lord |
| 1 Cor. 5:5 |
τῇ ἡμέρᾳ τοῦ κυρίου ἰησοῦ |
tē hēmera tou kyriou iēsou |
the day of the Lord Jesus |
| 2 Cor. 1:14 |
τῇ ἡμέρᾳ τοῦ κυρίου ἰησοῦ |
tē hēmera tou kyriou iēsou |
the day of the Lord Jesus |
| 1 Ths. 5:2 |
ἡ ἡμέρα κυρίου |
hē hēmera kyriou |
the day of the Lord |
| 2 Pet. 3:10 |
ᾗ ἡμέρα κυρίου |
hē hēmera kyriou |
the day of the Lord |
| Rev. 1:10 |
τῇ κυριακῇ ἡμέρᾳ |
tē kyriakē hēmera |
the Lord's day |
Beginning with the article, it has multiple forms in Greek to correspond with the various cases and genders of the noun. Nouns come in at least five cases, and can be masculine, feminine, or neutral in gender, as well as having either singular or plural forms--so there are many forms of the "ho" article, four of which can be seen in this table.
A Greek article can be optional. For example, in 1 Corinthians 5:5, it occurs both before "day" and before "Lord Jesus." Both of these are nouns, but because the article is already implied for the second noun in the sequence, it may not be explicitly required here and would be added more for emphasis or clarity. This does not change the meaning, but for readers of Greek it might help change the focus.
Consider that last phrase: "it might help change the focus." I could also say: "it might help to change the focus." The "to" is not required, does not change the meaning, but can be added for additional clarity or perhaps emphasis. Articles in Greek have some similarity to this in terms of their grammatical necessity--sometimes they are required, and at other times they may be optional.
In Acts 2:20, the word "day" is in the accusative case--making it the direct object of the verb. In 1 & 2 Corinthians, and in Revelation, it is in the dative case. In 1 Thessalonians and in Peter it is in the nominative (subject) case. These differences in sentence construction account for most of the variances. Unlike English, where a noun will appear in exactly the same form if used as a subject or as an object, in Greek these nouns are in different cases, indicative of their parts of speech.
With the exception of Revelation 1:10, the noun "Lord" in all of the verses is in the genitive case. This is the case which puts the noun in a belonging type of relationship and typically makes it the object of the preposition "of" which is why we then see "of the Lord" in the translation. The word "the", only explicitly found in the two texts from Corinthians, gets added to the others as a requirement of English grammar, as we would not say "of Lord."
In Revelation 1:10, the word "Lord" is an adjective, not a noun, in the dative case to match the subsequent noun "day" which is also in the dative case. The dative case often indicates the indirect object of the verb (direct objects would be in the accusative case). In this verse, however, the verb is translated as an intransitive linking verb and has no object. The dative case here places it as the object of a preposition--in this case "on", as in "on the Lord's day."
One might think it seems unlikely to have much significance in whether one says "the Lord's day" or "the day of the Lord," regardless of whether this minor grammatical difference is observed in English or in Greek. The two expressions are essentially equivalent in meaning.
However, one could make a case to say that John's expression varied from the others because he was not referring to the day of the second advent, but rather to the day which Jesus had claimed as his as noted in Mark 2:27-28.
27 And he said unto them, The sabbath was made for man, and
not man for the sabbath: 28 Therefore the Son of man is
Lord also of the sabbath. (Mark 2:27-28, KJV; cf. Matthew 12:8 and Luke 6:5)
John, therefore, references the Sabbath day; whereas Luke, Paul, and Peter are speaking of the time of Jesus' coming, as their context indicates.
Conclusion
There is no translatable significance to the additional article present in the expression in 1 & 2 Corinthians. These expressions are essentially equivalent to those of the other verses, except for Revelation 1:10. In Revelation, the word "Lord" is not a noun, but an adjective, and this grammatical variation may distinguish its meaning from that of the other verses. Contextually, the others all reference the time of judgment to be expected in the future on the "day" Jesus returns; whereas in Revelation "the Lord's day" indicates a present occasion, consistent with the Sabbath of the Lord.
