A powerful resource in our fight against temptation is the Medal of St. Benedict. The word "temptation" means a testing or trial. You are put in a situation in which it is difficult to do the right thing. The Lord Jesus Himself experienced temptations -- that is, situations in which it was difficult to act according to the Father's will. Scripture thus says that Jesus can "sympathize with our weaknesses," for He "has been tempted in every way as we are, yet without sinning" (Hebrews 4:15).
For Jesus the most difficult situation in which to do God's will came on the Cross and, thus, we rightly consider the Cross a triumph over sin and temptation. So great was the power of Christ's love, that even the torments of the Cross could not keep Him from doing what is right and just in the sight of the Father! In the Cross we find the power to persevere through temptation.
This brings us back to the Medal of St. Benedict. As the famous 19th century Benedictine abbot and spiritual writer, Servant of God Prosper Gueranger, has noted, the powerful effects of the Medal are rooted in the Cross and St. Benedict's devotion to the Cross.
The Medal features the Cross on one side and St. Benedict on the other. Furthermore, the image of St. Benedict has him holding the Cross in one hand and his Holy Rule in the other. More is said below about the letters and images on the Medal.
The point that needs to be emphasized is this: the devout use of the Medal is a way of invoking the power of the Cross of Jesus Christ together with the intercession of St. Benedict. For many, this invocation has proven effective in helping them to do what is right amid difficult circumstances.
Why does God provide special helps against temptation through the devout use of the Medal of St. Benedict? One reason seems to be that St. Benedict himself used the sign of the Cross -- for example, to ward off an attempt to poison him (e.g., see the story in Book 2 of St. Gregory the Great's Dialogues here). Another reason seems to be that St. Benedict became proficient, through God's grace, in resisting and overcoming traps placed by the Devil (see here, here, here, and here). These reasons are reflected in the Medal itself, for its abbreviations are prayers against the poison and the snares of the Devil and for urging us to follow Christ's Cross (again, explanations of these abbreviations are below).
The Medal may also be used to pray for a happy death, since St. Benedict is the patron saint of a happy death. He was well prepared when he died, having received the Holy Eucharist and being supported by his monks. The Latin words along the circumference and around the image of St. Benedict speak to this use of the Medal. These words are also described below. (St. Joseph is also the patron saint of a happy death, having presumably died in the presence of Jesus and Mary.)
In sum, the devout use of the Medal is an effective way of invoking the power of the Cross together with the intercession of St. Benedict. Part of devoutly using the Medal is to have it blessed (a blessing and other details about the Medal may be found here). While there is a tradition of having a Benedictine priest bless the Medal, it can be done by any ordained minister (bishop, priest, or deacon).
The Letters and Images on the Medal of St. Benedict
We first consider the back of the Medal, where the Cross features prominently. The letters C.S.P.B. around the Cross stand for Crux sancti patris Benedicti (Cross of holy father Benedict). On this side are also the initial letters for rhyming Latin prayers against the temptations of the devil. C.S.S.M.L. / N.D.S.M.D. = Crux sacra sit mihi lux! Numquam draco sit mihi dux! (May the holy Cross be my light! May the dragon never be my guide!). V.R.S.N.S.M.V = Vade retro Satana! Numquam suade mihi vana! (Get back, Satan! Never persuade me with your vanaties!). S.M.Q.L.I.V.B. = Sunt mala quae libas. Ipse venena bibas! (The things you offer are evil. Drink the poisons yourself!). On top is the Latin word PAX (Peace).
Now we consider the front of the medal, where is found the image of St. Benedict, holding the Cross and the Rule for Monks that he wrote. To his left and right are Latin abbreviations, again saying, ‘Cross of holy father Benedict.’ On his right, a broken chalice with a snake coming out of it recalls when St. Benedict was first a superior of a monastery and the monks tried to poison him, as alluded to above. Before drinking from the poisoned chalice, he blessed it with the sign of the Cross and the chalice miraculously broke, thus saving him from the poison. A raven on his left recalls when a priest who was jealous of St. Benedict’s virtue tried to kill him by giving him a poisoned loaf of bread. Knowing the priest’s malice, St. Benedict bid a raven to carry the loaf to a place where no one would be harmed by it and the raven obeyed. The Latin words around the circumference mean: ‘May we be fortified by his presence at our death.’ As noted above, St. Benedict is a patron of a happy death. Finally, some medals have EX-S-M-CASINO / MDCCCLXXX on the bottom. This is a Latin abbreviation for ‘From sacred Monte Cassino / 1880’ and it marks the official jubilee version of the medal. This version is struck only by Monte Cassino, the monastery that St. Benedict founded and where he wrote his Rule, and it was created in 1880 to commemorate the 1400th anniversary of the birth of St. Benedict and his twin sister, St. Scholastica.