In his messages to the pope, among other things, Scalfari had asked him whether "God forgives those who do not believe and do not seek faith."
Francis seemed to hint in his response that those who don't believe are not necessarily excluded from God's forgiveness.
"Given that — and this is the key point — God's mercy has no limits, if you go to him with a sincere and repentant heart, the issue for those who do not believe in God is to obey their conscience," Francis writes in his letter.
"Sin, even for those who have no faith, is when one goes against their conscience," he added. "To listen and to obey to (one's conscience) means to decide oneself in relation to what's perceived as good and evil. And this decision is fundamental to determining the good or evil of our actions."
Speaking about the church's relationship with Jews, Francis stresses that Christians, and humanity as a whole, should be grateful that Jews have "kept their faith" despite "the terrible tests of the past centuries."
In the letter, the Argentine pope also addresses one of the themes of his predecessor, Pope Benedict XVI, who had often condemned "relativism" — the incapacity of modern societies and men to recognize any "absolute truth," such as God — as one of the evils of our time.
For Francis, there is no such thing as an "absolute truth" if that means a truth that can stand by itself "without any relationship."
"Truth, according to the Christian faith, is God's love for us in Jesus Christ. Therefore, truth is a relationship."
Francis concludes: "Despite the slowness, the infidelity, the errors and sins it committed and might still commit against its members, the church, trust me, has no other meaning and goal but to live and witness Jesus."