This question is admittedly rather open-ended, even if grammatically it requires only a simple affirmative or negative. Your logical response would be another question: “Do I believe in what?” A belief about something, or confidence in a person (perhaps in oneself), is often what people are referring to when they speak of “faith”. But a faith that is more than a general or vague belief, one that is transformative and effectual, must have God as revealed in Christ as its object and basis.
God has indeed revealed Himself to this world in Jesus Christ, and we find the record of that in the New Testament scriptures. From the beginning of His ministry here among His people, Jesus presented Himself as the only proper object of faith, for the receiving of eternal life. The Gospel of John is filled with the Lord Jesus’ claims of being the Son of God, and alone worthy to be trusted in. “For God so loved the world, that He gave His only begotten Son, that whosoever believeth in Him should not perish, but have everlasting life” (John 3:16). “Ye believe in God, believe also in Me” (John 14:1). We could multiply references, and they are all precious. In order to clearly exclude any other object as legitimate for faith to be placed in, Jesus told His disciples that He would send the Holy Spirit down to earth after He went back to the Father, and that the Spirit would “bring demonstration to the world of sin . . . because they do not believe in Me” (John 16:8-9 JND).
We have just established from the Word of God that in order to gain eternal life, your faith must be placed in the Son of God, who came down from heaven to die for our sins and rose again on the third day. Refusing or neglecting to believe this simple gospel renders vain or futile any faith a person may think he has (I Corinthians 15:1-17). Now if you do not yet have the assurance of possessing eternal life in your soul, please do take that simple yet momentous step right now: Believe on the Lord Jesus Christ who came into this world to die for you. The change will be wonderful, you will become a new creation in Christ, and all things will become new and different for you.¹
In addition to presenting Christ as the proper object for our faith, we find one important qualifying adjective in the Word of God that is used when referring to personal “faith”. For the most part, the Spirit has not seen fit to qualify faith, nor to speak much of it quantitatively (see Matthew 17:20), as if to emphasize the overarching importance of faith’s divine Object that is everywhere assumed in the Word. However, because there is a need to guard against a superficial or careless use of the term, the adjective “unfeigned” is used twice with “faith” by the Apostle Paul, once in each of his letters to Timothy. I contend that one can only claim to possess eternal life if his faith is “unfeigned”, or sincere (I Timothy 1:5 and II Timothy 1:5).
We have some examples in Scripture of feigned or insincere faith, and I will mention just one of them briefly. Simon the sorcerer “believed also” when the people in that Samaritan city “with one accord gave heed” to Philip’s preaching of Christ (Acts 8:5-24). But notice there is nothing said of the Spirit falling upon Simon personally, and indeed, he is represented to us in the account as being just an opportunistic onlooker who gave in to covetous thoughts and words because of the miraculous evidence of the Spirit he saw in his countrymen. Peter’s condemnation of the thoughts of Simon’s heart indicate that no conversion had taken place there: “Thy money perish with thee . . . Thou hast neither part nor lot in this matter: for thy heart is not right with God . . . thou art in the gall of bitterness, and in the bond of iniquity.” Simon’s faith was proved to be counterfeit, and Peter possessed the spiritual discernment along with the apostolic authority that empowered him to condemn Simon for it. This same carnal impulse of professing faith because of miracles, rather than possessing sincere faith in Christ, is also addressed in John 2:23-25.
True faith is never the temporary impulse of the natural human heart; rather, it is a gift of God and a work of God², and is always accompanied by new creation life in the believer’s soul. The testimony of God’s Spirit with the believer’s spirit, and a desire in his or her heart to obey and to please Him³, provide abundant assurance of eternal life to the soul who has looked away from self to Christ in true faith.
¹ II Cor. 5:14-17 ² Eph. 2:8; John 6:29; Phil. 1:6 ³ Romans 8:14-16; I John 2:5-8