We know we are called by our response to the gospel; those who are called will naturally call on the name of the Lord.
The assurance of being called by God is evidenced by the desire and action of calling upon Him. As stated in Romans 10:13, 'Whosoever shall call on the name of the Lord shall be saved.' This expression of need and reliance reflects the work of the Holy Spirit within the believer. Additionally, as believers persistently seek the gospel and desire to know Christ more deeply, it affirms their calling, as seen in 1 Corinthians 1:26-27, which discusses God's choice of the foolish and weak to confound the wise. This ongoing pursuit and need for redemption is a hallmark of being among the called.
Scripture References:
Romans 10:13, 1 Corinthians 1:26-27, 2 Corinthians 13:5, Matthew 5:6, John 17:3
Commentary