Sefirat Haomer

Why are the days between Pesach and Shavuot called sefirat haomer instead of sefirah l’kabbalat haTorah? Why is the mitzvah of the omer accorded the special status of a brit? The answer to these questions reveal the true message behind the korban haomer;

The essential message of Passover is that the Almighty dominates and rules over His creation, while Shavuot focuses upon God's role as king. Both these traits find expression in the Omer counting, which is reckoned both according to days and weeks.