"Heathen" is the same as "nations" and "Gentiles." God's Word, as given to Abraham, indicated that all nations would be justified by faith (at this time, there was as yet no distinction between Jews and Gentiles). This was a unique revelation in a day when all the world's nations had already drifted away from monotheism and creationism and were relying on "works" to achieve whatever they may have understood as "salvation" or "justification."

Source:

KJV Defenders Study Bible, by Dr. Henry Morris, Ph.D.
Publisher: Thomas Nelson
Language: English
DEF 10 ISBN 0-529-10444-x
DEF 10-1 ISBN 0-529-10445-8