Parshat Vaetchanan

Devarim 4:15-19
For your own sake, therefore, be most careful–since you saw no shape when the LORD your God spoke to you at Horeb out of the fire — not to act wickedly and make for yourself a sculptured image in any likeness whatever: the form of a man or a woman, the form of any beast on earth, the form of any winged bird that flies in the sky, the form of anything that creeps on the ground, the form of any fish that is in the waters below the earth. And when you look up in the sky and behold the sun and the moon and the stars, the whole heavenly host, you must not be lured into bowing down to them or serving them. 
Devarim 4:39
Know therefore this day and keep in mind that the LORD alone is God in heaven above and earth below; there is no other.
Devarim 5:7-9
You shall have no other gods beside Me. You shall not make for yourself a sculptured image, any likeness of what is in the heavens above, or on the earth below, or in the waters below the earth. You shall not bow to them or serve them. For I the LORD your God am an impassioned God…
Devarim 6:4-5
Hear, O Israel! The LORD is our God, the LORD alone. You shall love the LORD your God with all your heart and with all your soul and with all your might.
Rabbi Adin Steinsaltz
But what is idolatry? Why is the Torah so concerned about it, why does the Torah caution so much against it, and what is the source of its attraction?
idolatry can manifest itself in many different ways, some of which do not necessarily resemble the traditional image of an idol. Anyone can take an object and cause it to become an idol … When one worships an object, he makes it an idol … we should not think that something has to be important or unique to be an idol; anything can be an idol. What is the halakhic definition of idolatry? “If one slaughters [an animal] as a sacrifice to the sun, the moon, the stars, the planets, Michael the Archangel, or a tiny worm, it is regarded as an idolatrous sacrifice.” (Tosefta, Chullin 2:18)
The essence of the matter is that anything that is removed from the framework that the Torah established and [is] set up independently becomes idolatry, even if this entity seems like something inherently holy or positive. [This is true even of an attribute of God.] … When one separates something from the whole, one holds on to a mere fragment of the pure form. The moment one removes it, no matter how holy it was, it turns into an idol.
This difficulty exists in many places and areas within the Jewish world. Just as half a Torah scroll is invalid and does not have the sanctity of a Torah scroll that is intact, so, too, when a piece is removed from the Torah, the piece has no sanctity but, rather, has the tuma of idolatry. It makes no difference whether that piece contains text concerning the mitzva of Torah study or the love of the Land. … If a person takes the Torah itself and empties it of all its content, then he is left with nothing — not even Torah — because he neglects the connection to the living God.
But so long as a person is crazy about one thing — he is crazy, regardless of what that thing is. … The test of legitimacy of such devotion is whether the object of one’s obsession is an element within a greater system, or whether it has assumed supreme importance in itself.
The urge to worship idols contains within it a very religious aspect – the desire to wholly devote oneself to something. … so as not to remain in a state of confusion, one is liable to choose one element and give it a separate status, thus clarifying and simplifying one’s world. This element is not necessarily forbidden, contemptible, or vile; it can even be something profound, important, and even holy. But it has been uprooted from its context, and so it loses its connection to true holiness.
I once met a Jew who wanted to declare publicly that all religions basically aspire to the same thing — love. It would not be correct to say that we are against love; we are clearly for it … it is just that the Torah contains many other things as well.
Moreover, the Torah contains many things that appear contradictory. One can make a whole collection of seemingly oppositional verses … which is correct? The answer is that both are correct. … knowledge is important, love is important, an vengeance is important … everything is important. This can be very confusing …
religious experience requires great wariness. … whenever one enters into a spiritual attachment or connection, even when it is for an important purpose, one must take care not to become involved in idolatry.
God wants us to love him Him “with all your heart” — the whole range of what is in the heart, the entire spectrum: the joy and the sorrow, the uplift and the letdown, the descent and ascent …
Rabbi Yehudah Leib
“With all your soul”–“with every single soul-breath that God has created in you.” And the meaning of “be-khol levavekha” is not “with all your heart,” as most people interpret it. But rather we need to become aware that each feeling we have is only the life-force that comes from God. 
This is the meaning of “LORD is one.” It goes beyond the fact that there is just one God, there is Hashem and nothing else. Everything that exists is only His blessed life, but it is hidden. … Therefore, the love of God has to be in every feeling a person has. This is “all your heart.”
Can the Torah itself be an idol? How could it be an idol?
Why does Rabbi Steinsaltz think that Judaism is not only about love? If God is both love and vengeance, how do you know what is the right action to take in a situation?
For Rabbi Leib all feelings come from God. Why do some feelings seem bad  or wrong? Are we supposed to act on all feelings? How do we know which feelings to act on, or which to reinterpret?
If devotion to one thing, taken out of its context, is idolatry, what about hate? Can extreme hate also be a form of idolatry? Or fear?