With regard to the question of the possible sources of Mk., various conflicting views have been held. The theory of B. Weiss, who believed in a fundamental "Apostolic Source" or "Original Gospel," supposed to underlie both Mk. and the Synoptic tradition in general, is now generally abandoned. The more fashionable theory that the sources of Mk. are to be re duced exclusively to the oral teaching of Peter is probably in process of abandonment. J. Weiss, who maintained that Mk.'s Gospel was "not a source, but a confluence of sources," attempted to distinguish (I) Petrine traditions, (2) stories of conflicts and discussions between our Lord and His adversaries, (3) isolated logic or sayings, with or without an historical framework, and (4) further popular traditions, of which the origin cannot be precisely determined. All these elements are no doubt actually represented in the Gospel ; the delimitation and reconstitution of the supposed written or oral sources is a different matter. Attempts at hypothetical "source-criticism" in a case of this kind are rarely profitable, and neither the theory of E. Wendling (who believed in an original Urmarcus, the work of an "his torian," revised and redacted successively by two subsequent writers, respectively designated by Wendling as "poet" and "theologian"), nor the more recent hypothesis of E. Meyer (a "disciples" source side by side with a source which speaks rather of "the Twelve"), is of any great value. Of greater importance is the question of Mark's possible relation to the Synoptic source known as "Q" (see the article GOSPEL). "Q," in some form, is probably earlier than Mk. ; and it has been thought that Mk. (which in the main is a narrative Gospel) may have presupposed "Q," and been written to supplement it. There are points at which it has been thought that Mk. actually depended on "Q" —e.g., the Beelzebub controversy (Mk. iii. 22-30), the catena of sayings in Mk. iv. 21-25, the discourse on the sending out of the Twelve (Mk. vi. 7–I I ), the sayings on discipleship in Mk. ix. 41-50, and the brief anti-Pharisaic discourse in Mk. xii. 38-4o. A comparison with the parallels in Mt. and Lk. sug gests that in all these cases the sayings in question were repre sented in "Q," and as a rule in a much fuller form. In these cases—and perhaps also in the exceedingly brief and allusive accounts in Mk. of the Baptist's preaching, and of the Tempta tion of Jesus—it appears in fact not improbable that Mk. pre supposed fuller knowledge on the part of his readers, or in other words that behind Mk. (not as a source which he incorporates, but as an already known document, with the contents of which he occasionally makes contact) the "Q" tradition is implied as being in some form familiar to the Christians of Rome.
It has been argued, lastly, that St. Mark's Gospel is "Pauline." It is certainly Gentile-Christian, and in its attitude to the Law anti-Jewish (cf. esp. Mk. vii. 1-23): but in Galatians St. Paul claims St. Peter's concurrence with his policy as regards "the gospel of the uncircumcision" (Gal. ii. 6 sqq.). There is little in Mk. that is distinctively Pauline—even the argument about the rejection and "hardening" of Israel (cf. Mk. iii. 5, iv. 11-12, vii. 6 sqq.), which exhibits affinities with the argument of Romans ix.–xi., may be set down to the account of the general missionary apologetic of the Church. St. Paul would have endorsed St.
Mark's Gospel; but so, probably, would St. Peter—the Roman Church in the next generation looked back to the two "good Apostles" as having harmoniously taught and worked side by side (Clem. Rom. ad Corinth. v. 3).
The second, or central, division of the Gospel extends from Mk. viii. 27 to Mk. x. 45, and is concerned with the theme of the coming Passion. The confession of Peter at Caesarea Philippi is not specially welcomed in Mk. (contrast Mt. xvi. 13-19), and the disciples are enjoined to say nothing about it (Mk. viii. 3o): the doctrine of the Passion, on the other hand, is proclaimed openly (Mk. viii. 32). It is by the road of suffering and death that the Son of Man must pass to His coming glory—the glory which the episode of the Transfiguration (a symbolic vision in which the representatives of Law and of Prophecy, seen for a moment in conversation with the Messiah, disappear to leave Jesus alone) heralds by way of anticipation (Mk. ix. 2 sqq.). The predictions of the Passion, thrice repeated (Mk. viii. 31, ix. 30-32, x. 32-34), sound like strokes of a bell—the Lord initiates His disciples beforehand into the mystery of His suffer ings and death. At the same time there is set forth also the doctrine of discipleship as a via crucis for those who would fol low. The true greatness consists in humility (Mk. ix. 33-37), it is needful to become as a little child (Mk. x. 13-16), the call is for utter self-sacrifice (x. 17-22)—wealth and worldly pos sessions are a hindrance (x. 23-31). The Son of Man came to give Himself a ransom (x. 45), it is a question of taking up the Cross after Jesus (viii. 34), of being prepared to drink of His Cup and to be baptised with His Baptism of blood (x. 38). The Gospel here becomes "virtually an impressive sermon addressed to the reader"—a sermon valid for all time, but peculiarly apt for the martyr-Church of first-century Rome.