Trials and temptations are tests of our character, tests of our faith, tests of our worthiness. Our faith in Christ's atonement for sin is either matured because of the trial or we fall because of our failure in succumbing to temptation. In this last of the six petitions that make up the Lord's Prayer, Jesus teaches a very real aspect of the life of the redeemed. Although salvation is assured for the elect, we also live in a tension between the kingdom of heaven that is already established by Jesus Christ in the hearts of the faithful and is not yet fulfilled. As such we remain as stewards of the mysteries of God [1 Cor 4:1] in a fallen world; participants in a spiritual warfare where Satan and his demons cause temptation for the purpose of bringing down the redeemed in Christ. Jesus teaches us to express our dependence upon God the Father in everything. To petition the Heavenly Father to be active in our lives; to protect us from the plots of Satan himself.
"lead us not into temptation, but deliver us from evil" [Matt 6:13]