According to fundamental Islamic teachings, knowledge is only beneficial when followed by good deeds and actions. However, we see that some scholars come short in regard to acting upon their knowledge. This can be a result of different reasons, just to name a few, the fact that they have just learned terms and lessons and aren't true scholars, disregarding their acquired knowledge and preferring the life of this world over the next, not using the insight they have gained effectively, thinking that what they have accomplished till now suffices them, forgetting that Allah and his chosen ones are always watching or over-estimating Allah's mercy and forgiveness, becoming subject to the temptations of Shaytan and putting off good deeds to the future, being tested by Allah and failing by thinking that the gains they have achieved in this temporal world are signs of Allah's satisfaction of them, etc. These are all deficiencies that one must strive to rid himself of and to step foot in the path of Allah's pleasure through awakening and His remembrance (remembering Allah and reminding oneself of all the things he has learned and knows).
With all of that said though, one should give the believers benefit of the doubt, especially the learned scholars from amongst them, and not to perceive them as not bearing any good deeds and behavior, because clearly, many good qualities aren't manifested and remain hidden inside oneself. Who knows, sometimes those who don't seem to be people of worship and good actions might actually be friends of Allah, although, as a rule, those who openly commit sins can never be part of this group and that is something that must be kept in mind.
There are different reasons to why there are individuals, who, despite possessing a great deal of knowledge, are lacking when it comes to action.
Some of the reasons for such a phenomenon are:
1- Not possessing true knowledge: Some individuals seem to be scholars, but deep inside, they don't have any divine knowledge and all they know are terms and words to help them secure certain positions for themselves in the eyes of others. As AbuDhar al-Ghifari (one of the greatest companions of Imam Ali (as)) says, these people will never sense the scent of Paradise. Obviously, such a lot, with their impure intentions, will try to capitalize on any opportunity in order to reach their initial goals, even if it means to invert religious teachings.
2- Preferring the life of this world over the next: In our everyday lives, we come across youth who are given the choice by their parents between getting what they want now, let it be a car, a vacation, a computer, etc., and financial and spiritual support after marriage (knowing that their parents will indeed fulfill this promise). Yet we see that their attachment and obsession for what they can have now is so much that it distracts them and makes them forget and overlook there permanent future, leading to their wrong decision!
Unfortunately, there are individuals among the scholars out there that are the same! Regarding one of these so called scholars (Balʻam Bāʻūrā), the Quran says: "Relate to them an account of him to whom We gave Our signs, but he cast them off. Thereupon Satan pursued him, and he became one of the perverse. Had We wished, We would have surely raised him by their means, but he clung to the earth and followed his [base] desires…"
Excessive obsession for material desires (be it wealth or position) is something very dangerous which is always shadowing scholars of religion, and they must ask Allah for help in confronting this danger. If this is not the case, as our imams have said, we must doubt in their religiosity.
3- Using religious insight: People, including scholars, sometimes do things that are justifiable in their eyes, and consider such behavior as good and decent, while the truth of the matter is the opposite.
When introducing this group, the Quran says: "Shall we inform you about the biggest losers in regard to works? Those whose endeavor goes awry in the life of the world, while they suppose they are doing good" Such a perception remains with these people until death, when they tell the angels taking their lives that they have done nothing good!
The reason for such a mistake and error is the fact that Shaytan would always trick them and embellish their shortcomings, and they couldn't make complete use of their religious insight and distinguish between truth and falsehood. It is as if these people have become blind in identifying the proper method and despite having this insight, they failed to use it and deviated from the correct path.
4- Deeming one's deeds to be sufficient: Some have good deeds in their books of deeds, such as jihad, zakat, hajj, etc., and Shaytan through his deception, has brought them to the wrong conclusion that what they have done till now, is enough for their salvation! This is while one should never feel satisfied and put performing good deeds aside, because this may even result in the ineffectiveness and eradication of their previous deeds.
5- Negligence of the fact that Allah and His chosen ones are watching: When people know and sense that they are being monitored and watched, they make less mistakes, but when this monitoring happens discretely, and the one monitoring isn't seen by them, they feel safer and more comfortable and think that they are freer in their actions, despite knowing they are being watched! It is due to this same reason that even though drivers are aware of the law, they go by it when there are police watching, but they don't have this sensitivity in places where there are hidden cameras, although they know that the cameras are there. Not seeing the police contributes to their negligence, not that there is no monitoring at all.
The same way, if we don't feel the presence of overseers such as Allah and His chosen ones, and don't see them with our material eyes, we will also forget and end up committing mistakes. It is because of this that Allah has reminded us of His supervision tens and hundreds of times. What we have to do is try to make this certainty that He is watching, deeply rooted in us in order to prevent and lessen our mistakes.
6- Hope in Allah's (swt) forgiveness and mercy: Some believers have no doubt that He is watching and monitoring their every move, the problem occurs when they have too much hope in His mercy and forgiveness, to the extent that their actions don't read with their words and knowledge!
Regarding these individuals, Imam Sadiq (as) says: "If you know that Allah is watching you and yet, you commit inappropriate acts in His presence while avoiding them in the presence of others, it is as if you have seen Him as the most insignificant of all overseers!" Of course, in a supplication, the imam brings an excuse for such behavior by saying: O Allah! My sin is not because I see you as the most insignificant of all overseers, but it is because of my knowledge that you will cover it and show patience and forbearance, and will not rush to punish me for it…!"
7- Procrastination: Sometimes, because of Allah's vow that he will accept the repentance of His servants, one of Shaytan's tricks is to give the sinner the feeling that there is always time for repentance and good deeds, and this causes them to put these matters off to the future! Here, the believers must remember that first of all, repentance at the time of death will do no good, and that secondly, death isn't something that can be predicted and that there are always chances that it is just around the corner! These two points make it indispensible that one doesn't procrastinate when it comes to good deeds and repentance.
8- Istidrāj: Some see their accomplishments in this world and their obtainment of God given blessings as signs of Allah's (swt) satisfaction of them, and in many instances, this may actually be the case, but one should always remember, when blessings are pouring down on a person who lacks good deeds, it might be the sign of Allah's plot (istidraj, i.e., graduality) against him that will have a bitter end.
The items listed above were some of the factors that contribute to one's actions not reading with his knowledge, even if he is a scholar, and we must all strive to take care of these matters so we don't end up being of those whose acts don't correspond with their words or knowledge.
Along these same lines, and keeping mind that the only way to meet Allah, is through actions and deeds, dhikr or remembrance of Allah, and reminding of Him are the best way for one to make use of his knowledge. What is meant is that one always tries to remember Him and to repeat what we know for ourselves and others. Repetitive worship, such as prayer, is a type of practical remembrance; when enough attention is paid to it, it removes negligence from the individual and prevents indecencies and wrongdoings.
In closing, it is necessary that this point be made, that scholars, like everyone else, despite their many qualities, may sometimes slip and make slight mistakes, but this won't harm their faith. Therefore, we must be careful not to be pessimistic about all of them or the other believers and not to consider most of them devoid of good character and qualities. The reason being that action isn't limited to the things that are tangible and that draw others' praise and attention. We have to doubt about the religiosity of those who try to show their religiosity to others and make themselves known as worshippers and people of action and must always remember that there may be many cases in which an act that doesn't stand out in our eyes will bring about many rewards, much more than normal worship will ever be able to. This makes it unacceptable for us to judge about others, because it might happen that those whom we think are at a low level of spirituality, are actually at a very high one compared to others!
However, there is one exception, and that is those who openly and shamelessly commit sins and consequently, whose backbiting has been allowed; they can't ever be part of the group of those who may have a higher status than we think.
 Hurr Ameli, Muhammad bin al-Hasan, Wasa'il al-Shia, vol. 16, pg. 280, hadith 21555, Aal al-Bayt Institute, Qum, 1409 AH.
 Ibid, vol. 7, pg. 145, hadith 8962.
 Shahid II (Second Martyr), Munyat al-Murid, pg. 142, The Office for Islamic Propagation Publications, Qum, 1409 AH.
 Muhammad bin Ya'qub Kuleini, Kāfī, vol. 1, pg. 46, hadith 4, Daar al-Kutub al-Islamiyah, Tehran, 1986.
 Nahl:28 "ما کنا نعمل من سوء".
 Nahl:63; Fatir:8; Anfāl: 48 etc.
 Muhammad:32-33, "...و سیحبط أعمالهم...و لا تبطلوا أعمالکم"; Hujurat:2; Hud:15-16; Ahzab:19; Baqarah:264 etc.
 Yunus:61; Tawbah:105; Ibrahim:42. Allah (swt) has announced his monitoring of man's acts using different wording. For example, the term khabir, has been used over forty times in the Quran.
 Majlisi, Muhammad Baqir, Bihar al-Anwar, vol. 67 pg. 386, hadith 48, Al-Wafaa' Institute, Beirut, 1404 AH.
 Ibid, vol. 95, pg. 84, an excerpt from the dua of Abu Hamzah al-Thumali.
 Nisa;18; Muminun:99-100.
 An'am:47; A'raf:95; Nahl:45 etc.
 An'am:44; A'raf:182.
 Qaf:45; A'laa:9; Dhariyat:55.
 Wasa'il al-Shia, vol. 1, pg. 79, hadith 179.
 Ibid, vol. 16, pg. 248, hadith 21478.
 Ibid, vol. 12, pg. 289, hadith 16328.