What does the Bible say about true Israelite?

In John 1:47, Jesus remarks about Nathanael, saying, 'Behold, an Israelite indeed, in whom is no guile.' This statement conveys that a true Israelite is characterized not just by heritage but by spiritual authenticity and integrity. The notion of 'no guile' implies a sincerity and honesty in one’s relationship with God. Nathanael's faith was a result of divine calling and grace, contrasting with mere external observance of the law. True Israel is formed by those who have been quickened by the Spirit and possess the faith that acknowledges Christ as the Son of God.