The short answer is “no.” The deeper answers are found in understanding what God describes (through the Bible) as true salvation, how we can understand if we have been saved, and what biblical assurance and perseverance means. Unfortunately, many of us have witnessed people who claim to be Christians but their lives and beliefs do not agree with God’s Word or they eventually “fall away” publicly from their previous confession.
“Examine yourselves, to see whether you are in the faith. Test yourselves. Or do you not realize this about yourselves, that Jesus Christ is in you?— unless indeed you fail to meet the test!” (2 Corinthians 13:5, ESV)
We are each called to examine the genuineness of our faith. True believers confess with their mouths publicly that inwardly they love, treasure and trust Jesus as their Lord and Savior, believing that Jesus is the Son of God and died on the cross and was resurrected from the grave (Romans 10:9-10). When God justifies us by faith in Jesus, He gives us His Holy Spirit within us (Ephesians 1:13-14) that outwardly evidences the inward reality of a new, saved heart through the fruit of His Spirit (Galatians 5:16-24).
More here on how to become a Christian and how to be sure you are a Christian:
“Keep a close watch on yourself and on the teaching. Persist in this, for by so doing you will save both yourself and your hearers.” 1 Timothy 4:16
God wants us to keep watch on ourselves the teachings we receive and give to ensure a right understanding of who He is and His Gospel plan. Once we are truly saved (justified), God continues His salvation through a process of change within us (sanctification), that continues until we meet Him in Heaven (glorification). God promises that His children are no longer under condemnation (Romans 8:1), can never be separated from His love (Romans 8:31-39), and will never be put to shame (Romans 9:33). God assures true converts that He keeps them in the faith (Jude 1:24-25) , finishes His saving work within us (Philippians 1:6), and promises their future resurrection (Romans 6:5) .
1 John is a great book to read that distinguishes true belief from false belief. It is written to encourage Christians to know and have confidence in the genuineness of their salvation (1 John 5:13). 1 John also shows in various ways that there are others who have publicly claimed to be Christians, but evidence lostness through their words and actions. Jesus’ parable of the soils is another place to see where there are some who have initially seemed to respond to the Gospel that eventual wither away or are choked out, evidencing their lostness by their fruitlessness (Luke 8:9-15).
“They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us.” 1 John 2:19
More verses on biblical assurance here: http://www.trustworthyword.com/assurance and perseverance here: http://www.trustworthyword.com/perseverance
Although true Christians will go through highs and lows, stumbling at various places in life, they will endure in their faith, preserving to the end in an evident way of increasing fruitfulness through God’s Spirit within them. If you are struggling with your own salvation, I encourage you to study these Scriptures to either confirm your faith or to expose your need to receive Jesus as your Lord and Savior. If you are asking this question out of concern for a friend or family member I encourage you to pray for God to open their heart to salvation and to use you to share His truth and show His love.
“But the one who endures to the end will be saved.” Matthew 24:13
“This charge I entrust to you, Timothy, my child, in accordance with the prophecies previously made about you, that by them you may wage the good warfare, holding faith and a good conscience. By rejecting this, some have made shipwreck of their faith, among whom are Hymenaeus and Alexander, whom I have handed over to Satan that they may learn not to blaspheme.” (1 Timothy 1:18–20 ESV)