There is an obvious reason why words such as "Rome," "Caesar," and "centurion" do not appear in the Old Testament. Malachi was written around 400 B.C. and the birth of the Roman Empire, although not universally agreed upon, occurred much later. Several events are commonly proposed to mark the transition from Rome being a republic to being an empire, including Julius Caesar's appointment as perpetual dictator (44 B.C.), the Battle of Actium (31 B.C.), and the Roman Senate's granting to Octavian the honorific title "Augustus" (4 B.C.). To the best of my knowledge, no other army had centurions. In the Bible, the word appears only in the Synoptic Gospels and the Book of Acts. John does not mention the Roman leader of one hundred soldiers in his Gospel or his letters.
Matthew speaks of two instances regarding centurions. In 8:10, "Jesus marveled, and said to them that followed, 'Verily I say unto you, I have not found so great (a) faith, no, not in Israel.'" Later, he wrote of the centurion at the crucifixion, "Truly, this was the Son of God" (27:54). Most scholars believe Matthew wrote his Gospel to the Hebrews. For him to paint a gentile soldier in a good light is amazing. Luke speaks of the same two instances in 7:9, and 23:47, but he includes something extraordinary. The centurion "glorified God, saying, 'Certainly this was a righteous man.'" That is high praise for an "enemy" of Israel! Mark speaks only of the crucifixion scene, and his quote is the same as that of Matthew.
The Book of Acts, also written by Luke, presents centurions in a very favorable light. In 10:1-48, Cornelius, a Roman centurion was the first Gentile to believe the Gospel and be accepted as a member of the Body of Christ. In 22:26, it is a centurion that listens to Paul, and stops Paul's scourging. In 23:17, another listens to Paul, and does what Paul asks. In 27:3, Julius, a centurion, treated Paul in a courteous manner. It took a storm and severe hunger for the centurion in Acts 27:9-44 to listen to Paul and to protect him from the rest of the soldiers. Apparently, the centurion rewarded Paul for his counsel by allowing him to stay a week with friends, and later, to have his own private "cell" where many of his friends could visit him (28:11-16).
I believe the reason the Bible reveals the positive actions of centurions during the early years of the Church, is because it was composed entirely of Hebrews. These passages clearly "messed with" the prejudice which characterized the early Church (Acts 10.1-11:18). Maybe there is a lesson for us here; if God could use Roman soldiers to bless believers, it is very likely that members of other races, nationalities, religions, and yes, even political parties can be used of God to bless the Body of Christ, and further His agenda. After all, God is no respecter of persons (Acts 10:34), so why are we?