On this show, I was referring to the Sons' pursuit of Abel, and how it brought Jax face to face with more details of his father's past and served to crack the facade of a wise and perfect role model. Abel's birth in the series premier, combined with his discovery of his late father's manuscript and manifesto, was the catalyst for the introspection and attempts to change his lifestyle and reform the club, which has been the overall story with which the show is concerned. When seen as a whole, we can better grasp how the process of searching for his son, leads him to once again discover his father. He learns of his father's betrayal of his family, and how John's questioning of his path and the path of the club led him to some very wrong places. He sees how these same weaknesses of his father caused his own son to be placed further from his reach, and his own weakness in succumbing to his father's doubts, as voiced by Fr. Ashby, lead him to let Abel go with his adopted family - and the resulting murders of that idealized, loving family. Jax was seduced briefly into following in his father's footsteps and abandoning his responsibilities, and that did nothing to forestall the continuing cycle of violence and death - it simply transferred the resulting consequences to others.

Up to this point on the show, even up to the final episode in Ireland, Jax has been opposed to the club's gun-running business. His occasional participating in schemes to facilitate that business have always been motivated by protecting his brothers in the club or fulfilling the immediate needs of the club for money, weapons or allies to protect themselves from other threats. He has even tried to get the club into the business of producing pornography as a superior alternative to gun-running, when the only superiority of that business was its legality (the Sons were introduced to that business by getting drawn into the violence, and by meeting the needs of the producers for capital and overhead - plainly the theoretical greater profits or less violence was NOT the appeal in Jax's mind).
How then could his actions in the finale be justified, when Jax must not only permit or enable, but actively encourage and bring about the murder of a federal agent and the murder of a former partner, the latter solely at the behest of their gun suppliers! There was NO other motive to murder Jimmy O. He had done the club no great wrong (the baby-napping & murder of Half-sack was done by a man fleeing Jimmy's punishment), and his agenda was compatible with Jax's - both wanted the Sons of Anarchy out of the IRA's gun business. The entire season arc not only fleshed out the history of the late John Teller, but it gave a negative side to that character, previously held up as the conscience and moral muse of the protagonist, his son Jax. What is more, it showed how Jax would plausibly be driven from his father's path of questioning the Sons of Anarchy and seeking to reform them to actively working with the "bad" guys in the club, killing for revenge and at the behest of their criminal partners, reconciling with his step-father and even bringing his girlfriend fully into the world of the club. Prior to this season, Tara represented to Jax the outside world and its values and ways, and the corrosive influence of the Sons of Anarchy was seen in how Tara's association with them led her to violent methods and lawbreaking herself. Jax resumed his relationship with her as he started down the path that led to a schism between him and Clay over the direction of the club, and that was not a coincidence. But for her to keep serving that narrative role in the future, he needs to commit to Tara in greater degree. As a mere casual girlfriend and not an official "old lady", at some point he would have had to choose Tara or the club, or she would have had to choose to demand Jax leave or else accept the club herself. Jax's abjuration of John Teller's path, as a result of his discoveries in this season, are what lead him to commit further to Tara and to allow them to start a family together. Now, because of the baggage and revelations and frustrating-at-the-time hoops they had to jump through to get Abel back, Jax and Tara are together "for good" for all intents and purposes. She is a complete & willing accomplice in their scheme to abscond with, and murder Jimmy and she is carrying Jax's child. But she is also exposed to the writings of John Teller, having read his letters to Maureen that the latter placed in Jax's bag, and she has not experienced firsthand the revelation of John's shortcomings and failures as a husband and father and club president. The man whose manifesto Jax presented to her as a moral guideline and path to redemption for the Sons has not been tarnished in her eyes, and she has personally witnessed the dangers and violence of the club lifestyle, with her kidnapping. Add in the newfound bond with her ex-biker groupie boss at the hospital and Tara is well-armed to carry on her role as an inspiration for Jax's conflict with the club and Clay. That conflict is the central engine of the show, and it cannot continue forever. Just as a bowstring or elastic band stretched out fully for too long loses its tension, so the status quo of the conflict between Jax and the club could not exist in stasis in perpetuity. The conflict needs to be altered and reshaped and refreshed. It must be superficially resolved from time to time (as it was by the developments of this season) in order to resume anew when the participants are exposed again to the sources of the conflict.