Can a Christian loose their salvation? The Bible says no.
The last point of Calvinism is: The perseverance of the saints. Perhaps a better summary would be: God’s preservation of the saints or God’s persevering with the saints. (BTW “Saints” is the word the New Testament uses for regular Christians.)
The Westminster Confession of Faith has a great definition of this doctrine. It says, “They whom God has accepted in his Beloved, effectually called and sanctified by his Spirit, can neither totally nor finally fall away from the state of grace; but shall certainly persevere therein to the end, and be eternally saved.”
Jesus put it this way:
“I tell you the truth, whoever hears my word and believes him who sent me has eternal life and will not be condemned; he has crossed over from death to life.” John 5:24
“My sheep listen to my voice; I know them, and they follow me. I give them eternal life, and they shall never perish; no-one can snatch them out of my hand. My Father, who has given them to me, is greater than all; no-one can snatch them out of my Father’s hand.” John 10:27-30
The Apostle Paul, Jesus’ follower and author of a large chunck of the New Testament said:
“He who began a good work in you will carry it on to completion until the day of Christ Jesus.” Philippians 1:6
“For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord.” Romans 8:38-39
According to the Bible, a Christian can never loose their salvation, fall beyond God’s grace, be un-adopted from God’s family, be un-justified or be un-redeemed. Christians will perseverance to the end.
This doctrine has been misunderstood by many. The doctrine does not say that Christians will not face any spiritual dangers or never fall into sin. Indeed they will face trials and fall into sin, just like all the “great” believers in the Bible. The doctrine simply says that if they are Christians they will persevere through all these trials and temptations and never loose their right standing before God.
Of course, this doctrine applies only to Christians. It does not apply to those who simply profess Christ, think they can live like they want and have a free ticket to heaven.