Dr. Michael l. Brown, a Messianic Jew and a leading figure in Messianic Judaism in the short video below gives a quick overview of how the Church “lost” its Jewish roots.
What Dr. Brown presents for the sake of time is an oversimplification of the long and complex relationship between Judaism and Christianity. For a more thorough, scholarly treatment I recommend The Ways that Never Parted: Jews and Christians in Late Antiquity and the Early Middle Ages by Adam H. Becker and Annette Yoshiko Reed.
This issue is very dear to my heart because learning the Jewish nature of Christianity has absolutely transformed my understanding of Christianity. I learned this through coming across New Testament scholarship. You can learn more about the history of New Testament studies reclaiming the Jewishness of Jesus here.