The fact that a Jew or Muslim or other believer can be saved does not negate the advantages of the Christian Faith. The fact that any non-Catholic can be saved does not make all paths to salvation equal.
The path to eternal salvation in Heaven is easier for believing and practicing Roman Catholics, much more so than for any other group. Catholics have every possible advantage in walking that path. Our path to Heaven is the most level, straight, and well-lit of any religion or belief system on earth. It is very likely that, of all the groups mentioned in this book, believing and practicing Roman Catholics will have the highest percent of saved souls, and the least time and suffering in Purgatory.
The further away a belief system is from Catholicism, the harder it is to attain salvation. As we move through a consideration of each belief system, the further we get from Catholicism on faith and morals, the less likely the person is to be saved, the more likely the person is to fall into grave sin, and the harder it is to repent and be forgiven.
An atheist can be saved, but his path to salvation is much more difficult than for any believer. Far fewer atheists are saved than Catholic Christians.
Roman Catholic theologian