Yeshua (Jesus) answered them, "You go astray because you are ignorant of both the Tanakh and the power of God. (Matthew 22:29)
The "Tanakh" is what we call the "Old Testament". Anytime the "New Testament" writers refer to the "Scriptures", they are referring to the Tanakh. Remember, they did not have the New Testament when they said and wrote those things. What we know as the New Testament canon did not form until 364AD at the Council of Laodicea.
Yeshua said that we go astray (error, make mistakes, fail, misunderstand, etc) because we do not know the Tanakh (Matt 22:29). We make errors because we do not understand the "Old Testament". We fail because we have failed to learn the Scriptures. Wow. We could stop right there and just meditate on that for a while.
It is interesting that many christians think that the "Old Testament" is somehow done away with, or that it is no longer important or relevant. They think that the "Old" has been replaced by the "New". In doing so, we treat the Word of God like a used car, replacing it with a newer model. This is wrong! The "New" does not replace or nullify the "Old", it is added onto. It is in addition to. It does not replace, it completes. This is why Yeshua said,
"Don't think that I have come to abolish the Torah or the Prophets. I have come not to abolish but to complete." (Matthew 5:17)
Our American mindset tells us that "Old is bad, New is good". This is why people stand in line for 11 hours to get the "new" iphone, when there is nothing wrong with their "old' iphone. We are trained to think that old is out of date and bad... and unfortunately this teaching is transferred over to our beliefs as well.
The Bible speaks of God as the "Ancient One", and in this case, Ancient is a positive thing. It means that God endures forever, He is built to last. He is "Everlasting" and "Eternal". The Bible also teaches us that "God does not change". "God does not change his mind". "Yeshua is the same yesterday, today, and forever". The "New Testament" is not a different testimony about God. It is the same testimony about the same God that is given in the Tanakh. In fact, we cannot truly understand God without both pieces.
The Jews have an incomplete understanding because they reject the "New Testament", and the christians have an incomplete understanding because they reject the "Old Testament". It is time for us to realize that the Entire Bible is given to us so that we can know God. Also, for us to completely understand the Messiah, and be able to show people who the Messiah is, we must understand what the Tanakh tells us about the Messiah. Remember that the apostles preached the Messiah from the Tanakh.
This means christians need to study the Tahakh. It means that we need to learn what the Scriptures teach about the Messiah. Christianity believes that Yeshua is the Messiah, but most people don't even really know what that means, because they don't understand the Scriptures.
Most christians don't actually know who the Messiah is, they just know his name is Jesus (actually his name is Yeshua). But we need to learn who the Messiah is, not just His name. Learn what the Scriptures teach about the Messiah. What you have been told by your preacher might not actually be correct. Search the Scriptures
"And beginning with Moses and all the Prophets, he (Yeshua) explained to them what was said in all the Tanakh concerning himself." (Luke 24:27)
Yeshua said to them, "This is what I meant when I was still with you and told you that everything written about me in the Torah, the Prophets, and the Psalms had to be fulfilled." Then he opened their minds so they could understand the Tanakh. (Luke 24:45)
"You keep examining the Tanakh... Those very Scriptures bear witness to me..." (John 5:39)
"According to his usual practice, Paul went into the synagogue; and on three Sabbath days he reasoned with them from the Tanakh" (Acts 17:2)
Many people are following a false Messiah, because they follow false teachings about the Messiah. There are a multitude of false teachings within christianity about Jesus. We need to study the Word of God for ourselves, so that we can know the truth.
We need to be like the Bereans, who "eagerly welcomed the message, checking the Tanakh every day to see if what Paul said was true." (Acts 17:11)
"Test everything. Hold on to the good." (1 Thessalonians 5:21)