Can I lose my salvation?

Not a single one of God’s elect can ever lose their salvation. God has guaranteed their final glorification in heaven according to His purpose for them (Rom 8:28-39). Jesus has promised to not lose a single one of them (John 6:39; 10:28-29; 17:2). Jesus will present every single one of them to His Father (Heb 2:13). They can prove their election sure by good works (II Pet 1:5-11).

Some verses in the Bible sound like a person can fall from grace (Gal 5:4), but that only means them falling from the proper doctrine of grace – they themselves are preserved in God to eternal life. Other verses in the Bible sound like presumptuous sins will take away eternal life, but the most severe of those passages – four of them in Hebrews – only refers to judgment on Israel.

See Also

For very detailed and thorough assurance of eternal life.
For the truth about once saved, always saved.
For the true interpretation of the Hebrews passages.