God's Word clearly tells us that Satan is the enemy of both God and man, describing him with such evil names as: "the accuser of the brethren" (Rev. 12:10); "the deceiver of the whole world" (Rev. 12:9); "the enemy" (Mt. 13:28); "the wicked one" (Mt. 13:19); "the father of lies" (Jn. 8:44); "a murderer from the beginning" (Jn. 8:44); and "the tempter" (Mt. 4:3)! More tellingly, Satan is actually called "the destroyer" (Ex. 12:23; Job 15:21; 1 Cor. 10:10; etc.). And in Hebrews 2:14, we read, "Forasmuch then as the children are partakers of flesh and blood, He (Jesus) also Himself likewise took part of the same; that through death He might destroy him that had the power of death, that is, the devil."
One has to ask, why would a loving God create such a being? We get some idea of why from the Book of Job. Although Satan does have the power to destroy one's property, one's health, and he even has the power to take one's life (Job 1:13-19; 2:7-8), he can only act against us with God's permission. Job 1:12 says, "And the LORD said unto Satan, Behold, all that he hath is in thy power; only upon himself put not forth thine hand." And in Job 2:6, we read, "And the LORD said unto Satan, Behold, he is in thine hand; but save his life." Satan described God's limitations on his desire to destroy Job, as being like a hedge preventing his access (Job 1:10).
Satan is an instrument, used of God, first to open our eyes to see our need for a Savior, then to reveal our continuing weaknesses, and our total dependency upon God for His mercy and grace! In fact, without "getting the results of a test," as student's, we are not aware of our lack of righteousness. James called the Law a mirror that reveals the truth about ourselves (Jam. 1:23-25). Earlier in the chapter, he wrote, "My brethren, count it all joy when ye fall into divers temptations; knowing this, that the trying of your faith worketh patience. But let patience have her perfect work, that ye may be perfect and entire, wanting nothing" (Jam. 1:2-4).
No matter how difficult the trial, God is using it for our ultimate good (Rom. 8:28-30)!