Receiving the Kingdom of Heaven
Rabbi Joshua the son of Korcha asks,"Why does the Shema
...come before the recitation of 'If you shall diligently hearken to...' in the daily liturgy of prayer? First one must receive the kingdom of heaven and then one may receive the yoke of the commandments.
m. Berakhot 2:2
More on the Shema:
Deuteronomy 6:4-9 Hebrew & English
What's Behind the Most Jewish Prayer? (aish.com)