One recalls the parables of the Last Judgement, where those welcomed into the Kingdom of God are surprised and ask "Where did we see you in need, a minister to you?" and Jesus answers "And the King replied, when I was thirsty you gave me to drink, when I was hungry you fed me, when I was sick and in prison you visited me. for if you did it to the least of these you did it to me." 
Among these might be found atheists. 
On the other hand, there were others who protested their condemnation: "We taught in your streets, we worked miracles in your name". They meet with a stern rebuke-"If you did it not to the least of these you did it not to me. It is not they who say, 'Lord, Lord' that enter the Kingdom of Heaven but they who do the will of the Father." 
While salvation is of grace, grace may be given to whomever God pleases to give it. This is a hedge against hypocrisy and a warning to the proud and self-righteous.  
Apparently many Catholics are not acquainted with the Gospel.