luke 3:23 And Jesus himself began to be about thirty years of age, being (as was supposed) the son of Joseph, which was the son of Heli, - Free Bible Online

      Lu 3:23-38. GENEALOGY OF JESUS.

      23. he began to be about thirty--that is, "was about entering on His thirtieth year." So our translators have taken the word (and so CALVIN, BEZA, BLOOMFIELD, WEBSTER and WILKINSON, &c.): but "was about thirty years of age when He began [His ministry]," makes better Greek, and is probably the true sense [BENGEL, OLSHAUSEN, DE WETTE, MEYER, ALFORD, &c.]. At this age the priests entered on their office (Nu 4:3).
      being, as was supposed, the son of Joseph, &c.--Have we in this genealogy, as well as in Matthew's, the line of Joseph? or is this the line of Mary?--a point on which there has been great difference of opinion and much acute discussion. Those who take the former opinion contend that it is the natural sense of this verse, and that no other would have been thought of but for its supposed improbability and the uncertainty which it seems to throw over our Lord's real descent. But it is liable to another difficulty; namely, that in this case Matthew makes Jacob, while Luke makes "Heli," to be Joseph's father; and though the same man had often more than one name, we ought not to resort to that supposition, in such a case as this, without necessity. And then, though the descent of Mary from David would be liable to no real doubt, even though we had no table of her line preserved to us (see, for example, Lu 1:2-32, and see on Lu 2:5), still it does seem unlikely--we say not incredible--that two genealogies of our Lord should be preserved to us, neither of which gives his real descent. Those who take the latter opinion, that we have here the line of Mary, as in Matthew that of Joseph--here His real, there His reputed line--explain the statement about Joseph, that he was "the son of Hell," to mean that he was his son-in-law, as the husband of his daughter Mary (as in Ru 1:11, 12), and believe that Joseph's name is only introduced instead of Mary's, in conformity with the Jewish custom in such tables. Perhaps this view is attended with fewest difficulties, as it certainly is the best supported. However we decide, it is a satisfaction to know that not a doubt was thrown out by the bitterest of the early enemies of Christianity as to our Lord's real descent from David. On comparing the two genealogies, it will be found that Matthew, writing more immediately for Jews, deemed it enough to show that the Saviour was sprung from Abraham and David; whereas Luke, writing more immediately for Gentiles, traces the descent back to Adam, the parent stock of the whole human family, thus showing Him to be the promised "Seed of the woman." "The possibility of constructing such a table, comprising a period of thousands of years, in an uninterrupted line from father to son, of a family that dwelt for a long time in the utmost retirement, would be inexplicable, had not the members of this line been endowed with a thread by which they could extricate themselves from the many families into which every tribe and branch was again subdivided, and thus hold fast and know the member that was destined to continue the lineage. This thread was the hope that Messiah would be born of the race of Abraham and David. The ardent desire to behold Him and be partakers of His mercy and glory suffered not the attention to be exhausted through a period embracing thousands of years. Thus the member destined to continue the lineage, whenever doubtful, became easily distinguishable, awakening the hope of a final fulfilment, and keeping it alive until it was consummated" [OLSHAUSEN].

JFB.