Yes, the Bible does teach that we are in the midst of an unseen spiritual conflict between God and Satan one in which Satan is constantly trying to gain victory over us. The Bible says, "For our struggle is not against flesh and blood, but against ... the spiritual forces of evil in the heavenly realms" (Ephesians 6:12).
These are sobering words, and they should warn us to be on our guard, and not ignore our responsibility to believe in Christ and live for Him. They also should remind us of our need to face the devil and his temptations with God's strength, and not rely on our own resources to meet Satan's challenges.
This is why the Bible tells us to "Put on the full armor of God so that you can take your stand against the devil's schemes" (Ephesians 6:11). Through prayer, through the truth of God's Word, through the Spirit, and through our fellowship with other believers we can resist the devil's assaults.
But you should remember two truths about the devil. First of all, he is a defeated foe! By His death and resurrection Jesus Christ overcame the devil, and someday He will come again to bring an end to Satan's influence over the universe. Second, when we know Christ, we are safe in God's hands forever. Is your faith and trust in Christ? Make sure of your commitment to Him today.