Day of Atonement (Yom Kippur), Fast Or Feast?

How Should We Keep and observe the Day of Atonement (Yom Kippur)? What are the Fathers instructions for this day? How did ancient Israel Keep this day. Is it a day of fasting as the religion of Judaism suggests? OR Is it an appointed feast day as is recorded in Leviticus 16, 22 and Numbers 29? Is the word Fast ever associated with Yom Kippur in scripture? OR Is is added by the religious leaders who write their own holy books? Come with me on this deep dive into Scripture as we seek the truth. The Day of Atonement, Fast OR Feast?