Gemara:


Ein Ayah: Wisdom is able to elevate a person above where he could have reached with belief without wisdom. In any area of expertise, there is a natural, lower level of skill. Until the higher level is achieved, the lower level is strengthened. When the higher level develops, the lower level is weakened and one has to be careful that the higher level will also fill in that which was lost from the lower’s diminishing. For example, a young child has a nature, like that of an animal, that prevents him from eating too much. When he gets older and his intellectual powers are increased, he is less protected by nature and needs intellectual protection. Thus, as the natural in a person is weakened, if his intellect will not take the role of nature, he can deteriorate to a point lower than animals, which are controlled by nature.
This idea appears regarding emuna (belief) as well. Through Hashem’s mercy on His creations, He leads them in the path of life that is always good for them to fix their moral status in the light of life. When one is young and cannot reach a different shleimut than one of simple belief, this belief is strong in him. He trusts his parents, teachers, and elders without internal confrontation. As he grows older, his developed sechel (intellect) provides a more important shield. He can direct his sechel to recognize truth and the value of true belief. Hopefully, whatever truths his simple belief had naturally brought him to will continue as a more intellectually based belief. With this belief, he should continue to follow and respect his parents, teachers and elders. The goal of wisdom is teshuva and good deeds, and therefore he should use his wisdom to reach greater spiritual heights than he had with juvenile belief without wisdom. Yet, he must hold on to the good things that he had as a child, guarding them with his sechel.
This is what the gemara warns that he should not use his sechel to distance himself from deferring to and respecting his parents (metaphorically, not "kicking" them). If one loses the good that emuna provided him, he has missed the goal. Had knowledge alone been sufficient, Hashem would not have provided us with natural tools. Rather, knowledge must be connected to good deeds, which are brought about by the abilities of his body and natural attributes. Therefore, sechel must carefully protect all of the good education that comes with a good nature.
This is why the gemara stresses acting for the right reason, not learning. Learning must be done for the purpose of carrying out good deeds. Only in that way does one respect the natural path that brought him to good and can now be strengthened by sechel. Those who do not act lishma want to use only the sechel and leave behind the path of straightness of good natural education. These people belong to the group who ruin the pillar of ethics and undo fear of Hashem, and it would have been better had they not been created. These are not the people about whom it is said that one should learn Torah or keep mitzvot not lishma for it will turn into lishma. That refers to people who follow the path of the simple without appreciating the greatness of Torah lishma. In contrast, here we are talking about "destroyers," who value sechel to the extent that they want to get rid of anything other than sechel. In truth, a healthy sechel realizes that the natural elements [including belief] are important pillars in reaching shleimut and wants to attach them to the sechel, with righteousness, truth, and subservience to parents, teachers, and those who are greater than they. They will turn to their predecessors to connect to the great sages of previous generations, the pillars of the pure Torah, enabling them to follow the path of life and goodness.