Tafsir of Al-`Ankabut 29:65

( So when they embark in the ship ) is connected to what the description of their state indicates. "Embarkation" (al-rukub) is the act of ascending upon a moving thing; it is transitive by itself, as in [the verse]: "That you may mount them" (li-tarkabuha). Its usage here and in similar instances serves to signify that the object being ridden is, in itself, of the category of places, and its motion is compulsory, not volitional. The particle fa (so) denotes immediate succession. The discourse contains the meaning of an ultimate end, as if it were said: They are diverted from the oneness of Allah, the Exalted, despite their acknowledgment of what it necessitates, [being occupied] with that which is most trivial and fleeting, heedless of eternal life, until, when they embark in the ship and encounter hardships, ( they call upon Allah, sincere to Him in religion ), meaning: they are in the state of one who has rendered his religion, creed, or obedience sincere, [behaving] as the believers do, in that they invoke none but Allah, the Exalted, and supplicate to no one else, for they know that none can remove hardships except He, the Mighty and Majestic.

There is mockery in this, regardless of whether "religion" (al-din) is intended to mean creed or obedience. As for the former, it is manifest. As for the latter, it is because they do not persist in this state; thus, it is contemptible in regard to its outcome. ( Then, when He delivers them to the land, behold, they associate [others with Him] ), meaning: they suddenly revert to polytheism, without any delay or hesitation.