It is entirely possible that "the wisdom of God" could be wisdom personified as we read of in places like Prov 1:20-33 & 8:1-36 however several other suggestions have been made in respect to what this could mean:
1) A saying that was recorded in literature or tradition that has not survived.
2) A lost book called "The Wisdom of God"
3) It has been translated "God in his wisdom has said'1
4) Jesus himself prophesying
It should be noted however that no book called "The wisdom of God" has been found, nor any other reference to such a book. Hendriksen also notes that "none of the usual quotation formulas occurring in the New Testament is here used." 2
The NAC commentary notes the following:
Selecting among these conflicting interpretations is also influenced
by how one interprets the tense (past, aorist) of the verb “said”
(Luke 11:49), “this generation” (11:50), and the reference to
“Zechariah” in 11:51. If this Zechariah is the Zechariah of 2 Chr
24:20–22, how could the present generation be held responsible for
martyrdoms occurring centuries before?3
Lange rules out option 1 & 2, whilst seeming to support option 4 when he says:
The Lord appears hereby to mean that through Him the wisdom of God
speaks personally to the children of men. The view that the Saviour
here cites an ancient declaration of God, lost to us (Paulus, Von
Hengel), is inadmissible, as “contrary to the analogy of all other
citations of Jesus, as well as to the evangelical tradition itself,
which attributed these words, with Matt. 23:34, to Jesus.” Meyer.
Perhaps we have here to understand a former declaration of the Saviour
Himself, and to compare Matt. 11:19. As the Son of the Father, who
spoke what He had formerly seen and heard with the Father, the Saviour
could with the best right name Himself ἡ σοφία τοῦ Θεοῦ, and perhaps
it is the recollection of similar declarations which has given John
occasion to designate Him decidedly as the λόγος τοῦ Θεοῦ. That here
only a ὕστερον πρότερον of form occurs (Neander, Twesten, Meyer), has
no proof. It was certainly not unworthy of the Saviour to cite His own
formerly-uttered word as that of the Incarnate Wisdom of God, and if
He did this we cannot then assume that He understood by the prophets
and apostles any one else than those of the New Covenant now soon to
appear in His place, and by whose rejection the measure of wickedness
should be fulfilled, and the murder of the prophets reach its
culmination.4
Hendriksen presents the following case:
The question arises, “But why make mention of this divine wisdom at
all in the present connection?” Could it be because God’s wisdom is
“that divine quality or attribute which reconciles seeming
irreconcilables”? In verses 49–51 Jesus speaks about the rejection of
“this generation.” But Paul makes clear—see Rom. 11:25–36—that the
very rejection of carnal Israel, by means of several steps, which he
enumerates, would result in the salvation of all God’s true people.
When that apostle meditates upon this he exclaims, “O the depth of the
riches both of the wisdom and the knowledge of God!” There is that
word wisdom again. It is true that in our present passage (Luke
11:49–51) that end result is not mentioned. However, an important link
in the chain of causes is definitely in view here, namely, the
rejection of carnal Israel (“so that the blood … may be exacted from
this generation”).5
It seems to this writer that evangelical scholarship shies away from the idea of this being wisdom personified and tends towards this statement simply meaning "God, in his wisdom, has said...' however this conclusion will be based upon the presuppositions of the exegete as there is no clear and obvious single answer to the question based simply upon analysis of the text in isolation. As Evangelical scholarship is not the only bible scholarship out there, doubtless others will have different frameworks in which the text is understood which will give more weight to the other options listed, e.g. Wisdom Personified.
In this writers opinion the opinion of the exegete should be in the lines of "This is what I believe it is mostly to mean because of X and Y" rather then a dogmatic statement.
Notes
1 NIV(84) reads, "Luke 11:49 Because of this, God in his wisdom said,`I will send them prophets and apostles, some of whom they will kill and others they will persecute.'"
2 Hendriksen, W., & Kistemaker, S. J. (1953–2001). Exposition of the Gospel According to Luke (Vol. 11, p. 642). Grand Rapids: Baker Book House.
3 Stein, R. H. (1992). Luke (Vol. 24, p. 342). Nashville: Broadman & Holman Publishers.
4Lange, J. P., & van Oosterzee, J. J. (2008). A commentary on the Holy Scriptures: Luke. (P. Schaff & C. C. Starbuck, Trans.) (p. 191). Bellingham, WA: Logos Bible Software.
5Hendriksen, W., & Kistemaker, S. J. (1953–2001). Exposition of the Gospel According to Luke (Vol. 11, p. 642). Grand Rapids: Baker Book House.
Ezra 7:25 καὶ σύ, Εσδρα, ὡς ἡ σοφία τοῦ θεοῦ ἐν χειρί σου κατάστησον γραμματεῖς καὶ κριτάς, ἵνα ὦσιν κρίνοντες παντὶ τῷ λαῷ τῷ ἐν πέρα τοῦ ποταμοῦ, πᾶσιν τοῖς εἰδόσιν νόμον τοῦ θεοῦ σου, καὶ τῷ μὴ εἰδότι γνωριεῖτε.
– C. Stirling Bartholomew May 12 '15 at 20:04