When Atticus talks with the Virgin Mary about the widow Mac Donagh
The Virgin’s smile became even brighter. “She prays to me daily, you know. And recently she’s been asking to keep you safe. So you must remain safe, Mr. O’Sullivan, and return my love to her. She has a beautiful soul.”
Atticus' friendship with Jesus counts as one, when you remember that Atticus considers Christianity one of the reasons that Druidism fell into obscurity. Just the fact that he and Jesus greet each other so fondly, and chat about the fun times they had, is downright wonderful.
Jesus' portrayal in Hammered should count as a Meta-example of Heartwarming. Having the author do things like point out Jesus' possible original skin tone, and his poking fun of people using Jesus' name in vain is funny, but the author never crosses any lines, and his having Jesus be nothing but compassionate in his appearance is genuinely touching.
Atticus asks Jesus how the widow Mac Donagh fares:
Jesus: Katie is at peace and with me.
Atticus: Please give her my love. I miss her.
Jesus: I will. She misses you too. You were a blessing to her in the sunset of her life.