How do we know that God's elect are always a remnant?

Throughout biblical history, particularly during the time of the judges, we observe that while the nation of Israel was established, the true spiritual Israel consisted of a faithful remnant. This concept reinforces the teaching that not all of Israel are God's elect. The narrative underscores that despite the discontent of the Jewish people, the Lord has always preserved a small group committed to Him, often referred to as the remnant. This truth remains evident in the New Testament as well, where it is clear that God's elect are called according to His purpose and grace, often facing opposition both from within and without.