The Lord Jesus Christ has many wonderful attributes, not the least of which is His faithfulness. That is, He is believable and trustworthy, sure to do all He promises. He will keep us from the evil one and from being overcome by evil in our lives, as promised in our text. Also, "God is faithful, who will not suffer you to be tempted |that is, 'tested'| above that ye are able" (1 Corinthians 10:13). Why does He care for us so?
In the first place, He is our Creator, and has a distinct purpose and will for our lives. Therefore all who are His can safely "commit the keeping of their souls to him in well doing, as unto a faithful Creator" (1 Peter 4:19). He will keep us to the end; Paul said, "I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ." Then follows his confident assurance: "Faithful is he that calleth you, who also will do it" (1 Thessalonians 5:23-24).
Even when we yield to the temptations along the way, and fall into sin, He promises: "If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness" (1 John 1:9), because He has paid the penalty for all our sins, and He is "a merciful and faithful high priest in things pertaining to God, to make reconciliation for the sins of the people" (Hebrews 2:17).
With such a faithful Savior and Lord, we surely ought to trust Him fully. In spite of this, we often doubt Him and His Word, but even this does not change His love toward us. "If we believe not, yet he abideth faithful: he cannot deny himself" (2 Timothy 2:13). Indeed, "God is faithful, by whom ye were called" (1 Corinthians 1:9), for His very name is "called Faithful and True" (Revelation 19:11). HMM http://www.icr.org/article/6704/