Can a Christian lose their salvation?

A person is not saved by their works. Neither can a person lose their salvation by their works.

"And you also were included in Christ when you heard the word of truth, the gospel of your salvation. Having believed, you were marked in him with a seal, the promised Holy Spirit, who is a deposit guaranteeing our inheritance until the redemption of those who are God's possession—to the praise of his glory."
(Ephesians 1:13-14)

"Being confident of this, that he who began a good work in you will carry it on to completion until the day of Christ Jesus."
(Philippians 1:6)

"Praise be to the God and Father of our Lord Jesus Christ! In his great mercy he has given us new birth into a living hope through the resurrection of Jesus Christ from the dead, and into an inheritance that can never perish, spoil or fade—kept in heaven for you, who through faith are shielded by God's power until the coming of the salvation that is ready to be revealed in the last time."
(1 Peter 1:3-5)

If you are really a Christian, you will:

(1) Confess that Jesus is Lord
(2) Obey the commandments of Christ
(3) Be miserable while sinning
(4) Keep yourself from the devil
(5) Love others (1 John)