So is this refutung “once save, always saved” or Calvinism?
It can be one or the other, not both.
Calvinists Do not hold to OSAS, therefore the author has lost ALL credibility.
I don’t think you know Calvinism because the 5th major tenet of Calvinism is ‘perseverance of the saints’ and it is the same as once saved always saved. The discriminating election of God, according to Calvin, makes it impossible for the elected and saved to lose his or her salvation.