Below is an excerpt from a sermon by John Piper. The link to the full text is at the bottom of this post. He is speaking primarily about loving people of different races, but the lessons are not limited to racial differences.
Ephesians 6:4: “Fathers, . . . bring them up in the discipline and instruction of the Lord.”
Part of that instruction is the Lord’s truth about racial differences and how we should think and feel and act about them. So fathers are put there by God, among other reasons, to help their children love people of different races. That’s my assumption in this message, and the rest of what I want to do in the rest of this message is give some examples of how to do that.
1. Help the children believe in God’s sovereign wisdom and goodness in creating them with the body that they have.
2. Help the children believe in God’s sovereign wisdom and goodness in making other people with the body that they have.
3. Help the children believe that they and all other children and adults are made in God’s image.
4. Teach the children that God tells us to do to others as we would like others to do to us.
5. Teach the children and model for them that their own sin is uglier than anybody they think is physically unattractive.
6. Teach the children that God loves them in spite of the ugliness of their sin and that he proved this by sending his Son to die for our sins and give forgiveness to all who would trust him.
7. Teach the children that because Jesus died for them and rose again, he becomes for them an all-satisfying Friend and Treasure.
8. Teach the children to love others who are different from them, not in order to be accepted by God, but because they already are accepted by God because of Jesus.
In order to teach all these things, you must model them and you must speak them. Model and affirm. Practice and preach.
I pray that you would embrace these 8 lessons, live them out for your children to see, and teach them how to do the same for their kids.
For the whole sermon, see http://www.desiringgod.org/resource-library/sermons/help-the-children-love-the-different-people