...and these whom He predestined, He also called
Only God can draw a person to faith in Christ!
God designed people for relationship with Him. Without a healthy, living spiritual relationship with God, the rest of our lives do not function like they should. Our relationships don't work well; we are unable to overcome persistent sin; we have no purpose greater than ourselves, nothing to live for beyond our own existence and pleasure.
Without a living relationship with God, the Bible describes us as spiritually dead (Ephesians 2:1). Because of this, unless God reaches into a person's life and regenerates their spiritual ability to know Him, that person will never recognize God's invitation nor respond to Him in faith. God has to "call" a person; God has to "draw" them to Himself (John 6:44).
So, when God puts it on your heart to share Christ with someone you know, and they have not shown any interest in the things of God yet, be sure that you set aside time to pray for God's work in their heart. Pray that God will "call" them to Himself, that He will enable them to recognize His invitation in their hearts and respond to Him.
That is what the Apostle Paul did. Romans 10:1 says, "Brethren, my heart's desire and my prayer to God for them is for their salvation." God wants you to do the same. He is calling you to help draw them to Himself.