The great Qur'an says,
They have taken their scholars and monks as lords besides Allah, and
[also] the Messiah, the son of Mary. And they were not commanded
except to worship one God; there is no deity except Him. Exalted is He
above whatever they associate with Him. http://tanzil.net/#9:31
Following a scholar should be in direction of obeying God.
When a believer (from any religion) see the scholars are teaching somethings that have conflict with clear and evident commands of God then they are worshiping that scholar instead of worshiping God.
For example divine books say God has no son. God is alone. But when a scholar comes and talks against this and says God has a son, when people accept him and follow him in fact they are worshiping him instead of God.
Currently, Christianity and Judaism have many laws against their original books. Their scholars keep original knowledge of books secret and feed the people their own interpretations.
This verse is not limited to Jews and Christians and applies to Muslims too. based on this verse:
Or do you think that you will enter Paradise while such [trial] has
not yet come to you as came to those who passed on before you? They
were touched by poverty and hardship and were shaken until [even
their] messenger and those who believed with him said, "When is the
help of Allah?" Unquestionably, the help of Allah is near.
Based on this verse all things that happened for past nations (specially stories of Bani Israel mentioned in Quran) will happen for Muslims.
QA: some people say according to verse 9:31 following the "Vilayat-e Faqih" is equal to Shirk. is it true?