How can one define a scholar?
The first and most important criterion is that he be capable of studying and understanding the Torah, a condition that calls for the highest possible degree of intellectual ability.
This, however, is only one facet of the fundamental outlook of the scholar.
It is not enough for him to be erudite and perceptive; he must also be a noble human being endowed with spiritual and humanitarian qualities.
One whose deeds are not compatible with his theories–either because his morals are not beyond reproach or because he does not strictly observe the precepts–cannot be regarded
as a true scholar and is therefore worse than an ignoramus.
The sages themselves said: "The deliberate errors of the unlearned are regarded as unintentional, while the unintentional mistakes of the scholars are regarded as deliberate."
It is not enough for a scholar to preach; he must also practice what he preaches, and when there is incongruence between theory and practice, a man can no longer be considered a scholar.
–Rabbi Adin Steinsaltz
From “What Is a Scholar?,” in The Essential Talmud by Rabbi Adin Steinsaltz