I consider worship of people to be idolatry. Even if the person one worships is a tzadik and truly righteous person. I base this on a few sources. One is the Tenach. The Old Testament. We can see many examples of this but one that comes to mind is the book of Daniel. There we have the friends of Daniel being pushed into a furnace and their general approach was to ask God for help. They did not pray through any intermediary.
Another source is the Talmud in Sanhedrin 62a. מאי שנא איהו מינן דידן. the gemara brings a case when someone says, "Serve me." One opinion in the Gemara is the idea in itself is absurd because people would ask, "What is the difference between him and us?" [But if people actually serve him then they are idolaters and he is a מסית ומדיח one who tries to convince someone else to serve a false god.]
[You could answer the person served God with great self sacrifice. But the the Gemara still considers it as absurd that anyone could worship another human being. And worship is not just the four regular types, also service according to its way עבודה כדרכה. for example if it is the way to bring charity to the person to have them pary for you, then this too would be considered idolatry.]
Another source is Maimonides. In the 13 principles of faith on Sanhedrin he goes into detail about idolatry. I forget the exact wording, but the basic idea is that God alone is proper to worship and praise and serve and nothing else. And also in the Mishna Torah he says idolatry is in its essence going to God through an intermediary. He says serving gods as gods in themselves was only a later derivative of idolatry.
The Nefesh HaChaim also says intention to bind oneself in spirit to a tzadik is idolatry.
Another source is the Talmud in Sanhedrin 62a. מאי שנא איהו מינן דידן. the gemara brings a case when someone says, "Serve me." One opinion in the Gemara is the idea in itself is absurd because people would ask, "What is the difference between him and us?" [But if people actually serve him then they are idolaters and he is a מסית ומדיח one who tries to convince someone else to serve a false god.]
[You could answer the person served God with great self sacrifice. But the the Gemara still considers it as absurd that anyone could worship another human being. And worship is not just the four regular types, also service according to its way עבודה כדרכה. for example if it is the way to bring charity to the person to have them pary for you, then this too would be considered idolatry.]
Another source is Maimonides. In the 13 principles of faith on Sanhedrin he goes into detail about idolatry. I forget the exact wording, but the basic idea is that God alone is proper to worship and praise and serve and nothing else. And also in the Mishna Torah he says idolatry is in its essence going to God through an intermediary. He says serving gods as gods in themselves was only a later derivative of idolatry.
The Nefesh HaChaim also says intention to bind oneself in spirit to a tzadik is idolatry.