Well, I don't know if you've ever seen the original "How the Grinch stole Christmas" or not, but there's a scene in there where the Grinch's heart grows many sizes. That's basically what happened to me when my first daughter was born, and then again when my second daughter and son were born.
I honestly never knew that a human being could love anyone as much as I love my children. They're constantly in my heart and mind, and every time I even think about them, I see them from the day that they were born unto their present ages.
They're truly a blessing from God.
How did it change my relationship with Christ?
Knowing how much I, as a father, love my children, it overwhelmed me to think how much my heavenly Father must love me in Christ.