A Pentecostal Question

Penetecost Sunday is this weekend which is a Christian holiday. However, the Bibilcal feast of Shauvot began Tuesday night May 14Th. Christians believe that they are part of the New Covenant as revealed in the New Testament. That New Covenant is first explained in Jeremiah 31:31-33: "Behold, the days come, saith the LORD, that I will make a new covenant with the house of Israel, and with the house of Judah: Not according to the covenant that I made with their fathers in the day that I took them by the hand to bring them out of the land of Egypt; which my covenant they brake, although I was an husband unto them, saith the LORD: But this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people." (KJV) Now on the Day of Pentecost (Acts 2:1-4), the Holy Spirit descended and filled the believers in the upper room and they all spoke with tongues. This is considered the birth of the church. Shauvot is a remembrance of the time when G-d gave the law to Moses. At the first Shauvot after the resurrection of Yeshua, the law was written on the hearts of man as opposed to tablets of stone. Now some believe that this occurs at "salvation" while others believe it occurs in a subsequent experience known by a variety of names, e.g. Baptism of the Holy Spirit, entire sanctification, Christian perfection, etc. Whenever you think it occurs, the uncontradicted fact is that the Torah is what is written on the hearts of men.

Now here is the question: if the law has been written on the heart of believers, why don't Christians obey the law of G-d, all of it?