What does the Bible say about salvation by faith alone?

The doctrine of salvation by faith alone is central to the Christian faith, as illustrated by the thief on the cross. In John's Gospel, we see that 'For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life' (John 3:16). This highlights that belief in Christ is the sole requirement for salvation. The thief exemplified this truth; despite his lack of any good works, his faith was enough for Jesus to promise him paradise (Luke 23:43).