Romans 12:5-7 (New King James Version)
5so we, being many, are one body in Christ, and individually members of one another. 6Having then gifts differing according to the grace that is given to us, let us use them: if prophecy, let us prophesy in proportion to our faith; 7or ministry, let us use it in our ministering; he who teaches, in teaching;
In the 1st Century, at the time of the writing of the Book of Romans, there was the gift of Prophecy. Had the Word of God been completely revealed at that time? No. Therefore, there was still the need for prophecy. However, God's Word is now completely revealed, and there is no more need for prophecy.