Paul says that the Scriptures of the prophets have been made known to all nations which leads to obedience of faithfulness. The Gospel of the Kingdom leads to obedience that only comes from faithfulness. Faithfulness to Yeshua Messiah will bring about obedience of Torah among the Gentiles. That is the message Paul is giving us. Faithfulness in Yeshua will bring transformation of our lives to desire to live according to the Instructions (Torah) of Elohim.
We are to present our bodies as a living and set-apart sacrifice acceptable to Elohim. This is not a new concept (Psalm 116:12-19, 50:13-15, 69:30-31). Regardless, if we are not obedient to Him, He is not interested in any sacrifice we have to offer (Jer. 6:19-20, Psalm 40:6-10). The point Paul is obviously making here is that we are to submit our lives to His will and to obedience to His Instructions (Torah).
Torah has jurisdiction and should be followed by a person as long as he lives. Paul never taught against following Torah. He says here a man should follow it all his life.
The philosophical question has always been asked, “How could a holy and loving Elohim who created such a perfect world allow evil and corruption to appear at all?” The only real answer to this question is that it was all in His plan.