The Principle of Contingent Causation: The Impossibility of Infinite Regress.

[Bucky Ball]

Anthony Flew became a Deistic Theist after many years of discussions and debates, including with Dr. William Lane Craig, God Bless him for it.

Anthony Flew, seemingly at the very door of Christianity and Salvation also said: "The evidence for the Resurrection is better than for claimed miracles in any other religion. It's outstandingly different in quality and quantity.” Amen. Well said. And yet we do not know if he made the final leap of faith before the end of his life; I hope for his sake that he did, so that he could now be in Heaven, or at least in Purgatory, and destined for Heaven in its own due time.

But all this goes to show, evidence does matter, arguments do matter, and they help people, in due time, who want to know the Truth, come to be saved. I agree with Dr. Craig's approach on the subject generally, which is also very Augustino-Thomistic, and places Logic and Reason in its proper place.

Your church, the Roman Catholic Church, (unfortunately for you) puts the lie to this entire piece of complete nonsense. 

The Catechism of the Roman church says :
1260 - Every man who is ignorant of the Gospel of Christ and of his Church, but seeks the truth and does the will of God in accordance with his understanding of it, can be saved. It may be supposed that such persons would have desired Baptism explicitly if they had known its necessity.. It's always been known as "baptism of desire" which the Magisterium expanded relatively recently when they updated the Catechism.

Unfortunately for you, you do not know even THE MOST basic tenets of the Roman faith. 

Assuming that Flew was, before and after any change he may or may not have had, including as a very old man, (his lucidity some have questioned),  a man of "good faith" acting in according to the understandings he had at any given time, he was saved and would have been saved. He didn't have "to make a final step". 
I get you like to think your exclusive club is necessary, as you are a religious snob, but it's not what the church says.
It's people like you that are responsible for the fact that 10 % of Americans are ex-Catholics.

You really should enroll in Catholicism 101, or better yet Comparative World Religions. 

This is known as the \”baptism of desire\”, an extra-ordinary way of salvation that occurs outside of the sacramental system. The Catechism also says:
1281 All those who, without knowing of the Church but acting under the inspiration of grace, seek God sincerely and strive to fulfill his will, can be saved even if they have not been baptized.

Paul told you faith was a gift. YOUR scripture tells you :
"By grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, so that no one may boast.” Ephesians : 2: 8-9

You are saying faith is the work of human acceptance. That is heresy.