Because of Winn-Dixie
How we cite our quotes:
"You're a mess," I told him. "I bet you don't belong to anybody." (1.21)
To Opal, "family" is the people who care about you. They provide physical and emotional care and make you feel like you belong—just like Miss Franny, Gloria, and even the Dewberry brothers.
My daddy is a good preacher and a nice man, but sometimes it's hard for me to think about him as my daddy, because he spends so much time preaching or thinking about preaching or getting ready to preach. And so, in my mind, I think of him as "the preacher." (2.1)
Check it out: there's a difference between a good man and a good daddy. The preacher is so disconnected from Opal that she can't even see him as her dad. Why? He's not doing what a true dad would do. He's got to break out of his shell or let her in.
"Are you looking for a home?" the preacher asked, real soft, to Winn-Dixie.
Winn-Dixie wagged his tail.
"Well," the preacher said. "I guess you've found one." (2.26)
Crack, crack on the turtle shell here. Winn-Dixie's I'll-love-you-forever-no-matter-what attitude penetrates even the preacher's padlocked heart. He can't help but accept a dog that accepts him.