I have several reasons to why I am a Messianic Jew, so I will start from the beginning. Why I believe God exists.
The arguments I usually use to explain my belief in God are the Mathematical argument, the Moral argument, and the Logical argument.

First Reason: Math
Math is in our heads and yet it perfectly works for almost everything. You have two apples, two is the number we use to say that there is that many apples. Math could not have been created by humans because it is infinite, it is what we use to define infinite. The existence of something that is in our heads, works for everything physical, and is infinite seems impossible without God.

Second Reason: Morals
Why shouldn't you steal? It is bad. What defines bad? What defines good for that matter? How can we define if something is good or bad? Murdering is bad, yes? Says who though? We cannot have morals without God. God defines what is good and what is bad because he is infinitely good.

Third Reason: Logic
Where did the universe come from? All arguments all have the same problem, logic. They all say the universe came from nothing. I even heard someone say that it came from the ashes of the last universe, well where did that one come from and the one before that? It is more logical to think someone, or something created it than to think it came from nothing.

Now that I have established the three reasons, I believe some God exists I will explain why I specifically believe in the Abrahamic God.
Jesus of Nazareth was a real person, almost every historian agrees on that, and he came and fulfilled the prophecies stated hundreds of years before he was born. He died on the cross with multiple witnesses, was buried in a tomb that was sealed off with an immovable stone and came back to life. Some could say the Disciples hallucinated, but more than one person cannot have the same hallucination. What if they were all liars another might say, no sane man let alone twelve would die on the basis of a lie. Saul, a devout Jew who was willing to kill every Christian he could see, but he had a vision and changed from killing Christians to teaching them. Last but not least, Yeshua (Jesus) came teaching the Torah and came to renew the Covenant, not replace them, for God does not change his plan. You cannot have the Torah and deny Jesus, and you cannot have Jesus yet deny the Torah.

May your name be inscribed in the Lamb's book of life. God bless you all my brethren.