The Passover was a festival that celebrated deliverance from Egypt.  Pentecost became a festival that celebrated the giving of the law through Moses.  Pentecost fulfilled the prophecy, “I will put My law within them, and on their heart I will write it; and I will be their God, and they shall be My people” Jeremiah 31:33b (NASB).  We need an internal guidance system vs. external law.  We need God inside of us to guide us in our living and doing.

“Moreover, I will give you a new heart and put a new spirit within you; and I will remove the heart of stone from your flesh and give you a heart of flesh.  And I will put My Spirit within you and cause you to walk in My statutes, and you will be careful to observe My ordinances” Ezekiel 36:26-27 (NASB).