Luke 18:13 New International Version
"But the tax collector stood at a distance. He would not even look up to heaven, but beat his breast and said, 'God, have mercy on me, a sinner.'
a
τῷ (tō)
Article - Dative Masculine Singular
Strong's Greek 3588: The, the definite article. Including the feminine he, and the neuter to in all their inflections; the definite article; the.
In https://biblehub.com/luke/18-13.htm, 21 versions translate it as "a sinner"; 6 as "the sinner".
Which is better?
The Greek phrase is definitely τῷ ἁμαρτωλῷ = "the sinner", but this does not necessarily compel the translators to translate thus.
However, Ellicott has this:
God be merciful to me a sinner.—Literally, to me the sinner, as though, like St. Paul, he singled out his own guilt as exceptional, and thought of himself as “the chief of sinners” (1 Timothy 1:15).
Similarly, the Cambridge Commentary has:
God be merciful to me a sinner] Rather, O God, be merciful to me the sinner.The word for ‘be merciful’ means ‘be propitiated’ as in Hebrews 2:17. He speaks of himself as the chief of sinners, 1 Timothy 1:15.
Also Jamieson-Fausset-Brown Bible Commentary
be merciful—"be propitiated," a very unusual word in such a sense, only once else used in the New Testament, in the sense of "making reconciliation" by sacrifice (Heb 2:17). There may therefore, be some allusion to this here, though not likely.
a sinner—literally, "the sinner"; that is, "If ever there was one, I am he."
Personally, I agree - this man is in no doubt that is not just any sinner but a great sinner - THE sinner. In the absence of the article, the Greek simply means that the man considered himself in the category of sinners. However, the force of the article here is to make him the great sinner with particular sins that specifically need repentance and mercy.
Thus, Jesus could follow this with: "I tell you that this man, rather than the other, went home justified before God."
