One must be very careful in honoring and fearing his father and mother.
The three partners in one’s creation:
There are three partners involved in the creation of a person; G-d, the mother and the father. G-D blows the soul into the body thereby giving it the ability to hear, see etc. The mother donates the red parts of the body while the father donates the white parts, such as the bones, brain. For this reason it is proper to honor all three partners, each for their part in one’s creation.
Why does honoring one’s parents not constitute the prohibition of Shituf, which is giving credence to anyone else other than G-d?
It is a known pillar of our faith that it is forbidden to pay honor or respect to the constellations and stars for their involvement in the blessings which we receive. One who does so is liable for idolatry. The following question hence extends towards honoring one’s parents; how does this not constitute idolatry which consists of paying respect for anyone other than G-d. Possibly one can answer that it is only because the constellations and stars do not have free choice that one is therefore forbidden in paying them respect. One’s parents however had free choice in bringing one into the world, and hence played a deciding role in ones creation. Therefore they deserve to be honored. On a deeper level it can be explained that every Jew contains a portion of G-d above, thus honoring Jewish parents which contain a part of G-d in them does not contradict at all G-d’s unity.
Why gentiles were not commanded to honor their parents: It is for this reason that gentiles were not commanded to honor their parents, despite this being a basic morale concept, being that commanding them to do so would constitute heresy in G-d’s unity [shituf].
 Kiddushin 30b
 As a man “Ish” and woman “Isha” both contain the Yud and “Kei” of G-d’s name. Thus it is considered that G-d is dwelling within them, and by them being honored one is likewise honoring Him. When however there is lack of honor, then G-d does not dwell his name of Yud “Kei” within the parents and they thus remain “Eish” Eish”, fire with fire. The reason that the parents get punished for this is because they brought up a son which does not honor them. [Agados Maharsha]. Based on this perhaps one can explain the connecting between chapter 240 in Orach Chayim and this current chapter which is also 240. As when parents fulfill the proper form of kedusha in their marriage, which is the laws mentioned in 240 Orach Chayim, then they merit that the sons fulfill the laws of Kibud Av Vaeim in 240 Yoreh Deah.
 Kiddushin 30b; Nida 31a
 Likkutei Sichos 36 p. 90
 This answers why this honoring of parents, which is honoring something else other than G-d, is not considered heresy in G-d’s unity.