Attitude toward unbelieving parents:
Let us look at Noble Verse 31:15 "But if they strive to make thee join in worship with Me things of which thou hast no knowledge, obey them not; yet bear them company in this life with justice (and consideration), and follow the way of those who turn to me (in love): in the end the return of you all is to Me, and I will tell you the truth (and meaning) of all that ye did."
Let us look at Noble Verse 9:23 "O ye who believe! take not for protectors your fathers and your brothers if they love infidelity above Faith: if any of you do so, they do wrong."
There is no contradiction in the above Noble Verses !.
In Noble Verse 31:15, Allah Almighty orders us not to follow even our parents if they request from us to worship other gods than the Almighty GOD, Allah. However, even if the parents are pagans or infedels, we still are ordered by the Most Merciful Allah Almighty to be there for them and to help them in life.
In Noble Verse 9:23, Allah Almighty orders us not to take even our parents if they were pagans as guidance or leading example that we must follow. Children always take their parents as the high example that they follow. In Noble Verse 9:23, we are ordered not to consider the parents as our protectors (top examples) and we must not take everything they say or do for granted because they are in wrong doing.