Its a pretty controversial topic to bring up to a christian. When you go through the old testament, you may begin to gather that Jesus is not the messiah they were fortelling toward, but if you dig a little deeper you may also find that he should also be considered a false prophet.

***Long prologue***
I haven't done much in the way of religion lately. Its not that I think I've "figured it all out", I just lost interest. I've moved on to just living and hopefully I'll be starting to have a family in the next couple years. But I do retain information like a shamwow unwringed that sits in the moist recesses of the underside of a sink. I do know a thing or two from my youth. I grew up in a christian household and over the years I began to have more and more questions, since it doesn't make a whole lot of sense. I started with the obvious place, mostly because I lived in an intolerant small midwest town and had no access to any other religious sources than christianity. I did find some problems but nothing damning. So when I moved to a bigger town and found a mosque, that was my next venue. But Islam is a its own thing. It has its disagreements with christianity but overall it is it's own thing entirely. In all honesty, I think Islam is a much more pleasant religion than christianity. But I digress.
Honestly, living here in the midwest it is hard enough to get any info on Islam, but it is near impossible to find an actual synagogue in the state that birthed the KKK. In Ft Wayne, there was a synagogue but it was one of those reform ones where they're basically christians only without the Jesus part. In the town where I live now, it is the same. There's a mosque, but all the synagogues aren't really "Jewish" but reformed. Lucky for me, the internet is becoming more robust with information. I learnt a lot about actual Judaism leading up to 2014. Back in 2010 I bought a Tanach but without the Jewish perspective its just a slightly different-worded old testament. Plus, since then I've found parts of it through the guidance of Jewish people that christians never bring up in Sunday school. Now we were getting somewhere.
Obviously the biggest question I had was one I had a mere curiosity to know, why the Jews don't believe Jesus was the messiah. There are actually quite a lot of reasons why not. And it opens the door to many other interesting old testament answers to christian beliefs.
***End prologue***

First thing to know is how god is portrayed in the old testament. It says all over in the old testament that god is incorporeal, meaning that he assumes no physical form (eg Exodus 33:18-20; Deuteronomy 4:15). In the old testament it says of god, he is eternal, above time. He is Infinite, beyond space. He cannot be born, and cannot die. So anyone who believes in the old testament saying that god assumes human form - as is the claim of Jesus - it would make god small, diminishing both his unity and his divinity. “God is not man to be capricious, or mortal to change his mind.” (Numbers 23:19).

Jews have declared their belief in a single unified god twice daily ever since the giving of Torah at Sinai –almost two thousand years before christianity. The catholic idea of the trinity suggests a three part deity: “The Father, the Son and the Holy Spirit.” (“Matthew” 28:19). Contrast this to "the Shema", the basis of Jewish belief: “Hear, O Israel! The Lord is our God, the Lord ALONE.” (Deuteronomy 6:4). Jews declare the Shema every day, while writing it on doorposts (Mezuzah), and binding it to the hand and head (Tefillin). This statement of god's one-ness is the first words a Jewish child is taught to say, and the last words uttered before a Jew dies.
In Jewish law, worship of a three-part god is considered idolatry; one of the three cardinal sins for which a person should rather give up his life than transgress. This explains why during the Inquisitions and throughout history, Jews gave up their lives rather than convert.

But let's get right to it. How is Jesus a "false prophet?" One of his central ideas outright contradicts the old testament, the claims that he was god in the flesh. Another thing he did was talk about god being a 3 part god. And lastly, he claimed to be god's son; since god is neither human nor of this world the old testament and Jewish tradition assert he does not beget. So where in the old testament is a coming of false prophets mentioned?

Quote Originally Posted by From Deuteronomy chapter 13
Be careful to observe only that which I enjoin upon you: neither add to it nor take from it. If there appears among you a prophet or a dream-diviner and he gives you a sign or a portent, saying, ‘Let us follow and worship another god’—whom you have not experienced—even if the sign or portent that he named comes true, do not heed the words of that prophet or dream-diviner. For the Lord your God is testing you to see whether you really love the Lord your God with all your heart and soul.
According to the old testament, god = no one. From a Jewish perspective, Jesus was trying to get people to follow a god the Jews "had not experienced": A god that begets, a god that takes human form, and a god that is more than one. It was the Jewish who wrote the old testament after all.

The new testament, including Jesus himself, spent an awful lot of effort to prove there's a devil that equals god and rules the worldly realm. Aside from the fact that the old testament says that god rules over the world and makes all things happen (including evil), there is no devil according to the old testament.
The word "satan" itself means adversary. So its mainly used to describe anyone who opposes the Jews. Its also used as a verb, like this:

Quote Originally Posted by Numbers 22:22
וַיִּחַר-אַף אֱלֹהִים, כִּי-הוֹלֵךְ הוּא, וַיִּתְיַצֵּב מַלְאַךְ יְהוָה בַּדֶּרֶךְ, לְשָׂטָן לוֹ; וְהוּא רֹכֵב עַל-אֲתֹנוֹ, וּשְׁנֵי נְעָרָיו עִמּוֹ.
But [Elohim] was was incensed at his going; so an angel of [JHVH] blocked/thwarted (or satan'd) his path.
There is, however, an angel under god's power called Satan or the Angel of Opposition (Satan) within a few old testament stories. Job is an obvious. But some less obvious examples:

Quote Originally Posted by from Zechariah Chapter 3
He further showed me Joshua the high priest, standing before the angel of the Lord, and Satan standing at his right side to accuse him. But the angel of the Lord said to Satan, "O Satan; may the Lord who has chosen Jerusalem rebuke you! For this (Joshua) is a brand plucked from the fire." Now Joshua was clothed in filthy garments when he stood before the angels. The latter (Satan) spoke up and said to his attendants, "Take the filthy garments off him!" And [Satan] said to him, "See, I have removed your guilt from you, and you shall be clothed in priestly robes." Then he gave the order, "Let a pure diadem be placed on his head." And they placed the pure diadem on his head and clothed him in priestly garments, as the angel of the Lord stood by.
Quote Originally Posted by from II Samuel chapter 24
The anger of the Lord again flared up against Israel; and he incited David against them, saying, "Go and number Israel and Judah."
Quote Originally Posted by from I Chronicles chapter 21
Satan arose against Israel and incited David to number Israel.
A rabbi once pointed this out to me. It is a proper noun in this case. But in all these stories Satan is always an angel of god, subservient to god, and a messenger of god. In the old testament, it says humans were created to have freedom of will; but not the angels. In christianity its believed this angel rebelled against god, took angels with him, and suddenly rivaled god in power. The old testament raises problems with this idea. The most obvious is that without free will, angels cannot rebel against god. But also, angels are never said to be anywhere near as powerful as god. So the whole idea of the devil is preposterous even if you believe in the old testament as christians claim to.

So who is the angel Satan in the old testament? The Jewish believe he is an angel that god uses to test the Jewish people by standing in their way of spirituality, to tempt them. It is believed Satan is a necessary part of life, because it is Satan who allows for 'being good' to be virtuous. It is believed that if it was so easy to be good, no one would even try. Satan is sent by god, they believe, to inspire people to better themselves and have a reason to be virtuous for god etc.

Anyways, that's what I know on the matter. Basically, christianity is rooted in the old testament which refutes a lot of what they believe, making it an oxymoron. Which I find interesting. Any thoughts or questions?