text: Collaboration is not my word it is from the Catechism 2025, my word would have been cooperation. God does not force His grace upon us, He offers it to us and we having free will are capable of resisting it. Acceptance therefore is an act of will, a work. You don't mention the other thief who in cursing Jesus rejected His offer of salvation. Ultimately both thieves were responsible for their fate.
  One can sin mortally and thereby lose their baptismal justification but not necessarily lose their faith. I still believe, have faith in God when I am not in a state of grace. Luther stated that loss of justification was the result of loss of faith. 
  I told you it was a complex issue. Protestants and Catholics have been arguing over it for hundreds of years.