Eliyahu on Mount Carmel asked the People of Israel, "How long will you jump between two extremes? If the Lord is God then serve him, but if the Baal is God then serve him."
Why did they not just answer "Both?" After all that was the ancient Canaanite religion: that the Lord [Yod he vav he] is the ruler of the heavens and the Baal was the ruler of the Earth. I think that the point of Eliyahu was that there can be only one First Cause. [There can only be one first of any series.] This is the same point that the Chovot Levavot brings in answer to this same question. [That is the first book of Musar The Obligations of the Hearts by Ibn Pakuda
I was reading that whole incident and I had a few observations. One is the Eliyahu was eating bread and meat in the morning and bread and meat at night. That was from what the ravens were bringing to him. That seems odd in itself in terms of tractate Hulin. [The sages said the meat was coming from the table of Ahav. So the only problem was בשר הנעלם מן העין. Meat that was hidden and then found. But there is an answer to that.]
Another thing is that even after the People of Israel had repented, still the later prophecy when Eliyahu was at Mount Horev said to anoint a king on Aram, then one of Israel and then Elisha who would kill all those who had bowed before the Baal. And you see later that in fact only 7000 people were left of all Israel. That is another thing that is hard to understand.
Another point is that the way the Canaanite religion was, was that the Lord is the God of the heavens which means he has final and absolute control over the heavens. The same with the Baal on the Earth. So the point of Eliyahu was that God has the final and absolute control of both heaven and earth. But we do find in the Torah that people did ask prophets to pray for them. Like Hezekiah asking Isaiah to pray for him. So the idea that there can be an intermediary between one and God is possible. But "asking" is not the same thing as "praying." "Praying" is when one knows there one he is praying to is the final court of appeals and has absolute power over the subject one is asking about. "Asking" is not the same thing. And one does not worship the intermediary. Only askes to pray for one.