Abraham is the clearest example of someone who was saved by his faith, apart from his works. God spoke, Abraham took God at His word, believed God, and God credited that belief to him as righteousness. To be credited as righteous means to be absolved of all guilt. This has always been the basis of salvation, even before Abraham. This righteousness, freely given, does not need to be maintained or sustained by good works. Since all people have sinned, all have the same spiritual need, the one true God saves all the same way, on the same basis, for all times.