Prayer is, of course, a mystery, as is our relationship with God in general. However, we are absolutely supposed to pray for those who do not believe in God, both for their conversion and for the forgiveness of all their sins. The Bible and Tradition teach us that praying for others can forgive their venial sins, as well as gaining for that person grace and the powerful intercession of saints, particularly the Blessed Virgin who has led so many to her Son, as she did at Guadalupe. And, you could and indeed should also pray that you may do all you can to help that person come to God. This is not always correcting them or evangelizing verbally to them, however; repeating those can quickly become a cudgel. Rather, you should first and foremost lead that person through the example of your own holiness, through courage, lack of embarrassment at your faith and in the Church, and through acts of charity, both big and small, such as always treating people, especially that person, with respect, dignity and compassion, never judging or criticizing, always acting with the love of Christ. As His Holiness Benedict XVI once said, “There are really only two effective means of apologizing for the Christian faith: the saints [holiness] and art.” (paraphrasing from memory) So yes, do all these things and always live in hope, for indeed, in hope we are saved. And always remember: our war is not with flesh and blood, but with Satan, his demons, and sin, which are the real culprits.
I pray for the non-believer of whom you speak, and for all those in the world, including Catholics, who do not believe in God, who have not accepted Christ, who are experiencing despair or doubt, or who are living as though God did not exist or as if He does not love us. I pray for the forgiveness of all their sins, that they may be led to conversion to experience “life, and to the fullest” from Christ who if Life, and that all their ills and afflictions may be healed and suffered gracefully. I particularly pray for all those who are leading others to unbelief, both active nonbelievers and Christians who misrepresent the Faith, particularly all those in politics and the media. I ask for the intercession of the Blessed Virgin Mary, your friend’s guardian angel, St. Michael the Archangel, St. Paul the Great Convert, and St. Edith Stein. God bless.
St. Michael the Archangel, defend us in battle
Be our protection against the wickedness and snares of the devil
May God rebuke him, we humbly pray, and do thou
O Prince of the Heavenly Host, by the power of God
Thrust into Hell, Satan and all the evil spirits
Who prowl about the world, seeking the ruin of souls.
Amen.