The gifts and the call of God are irrevocable

"For the gifts and the call of God are irrevocable."  (Romans 11: 29)

Which gifts?

"The spirit of the LORD shall rest upon him:
a spirit of wisdom and of understanding,
A spirit of counsel and of strength,
a spirit of knowledge and of fear of the LORD,
and his delight shall be the fear of the LORD.
Not by appearance shall he judge,
nor by hearsay shall he decide."  (Isaiah 11: 2 - 3)

Which call?

"I have chosen you from the world to go and bear fruit that will last."  (John 15: 16, 19)
"I will bear a witness to you in the world,O Lord.  I will spread the knowledge of your name among my brothers,alleluia!"  (Psalm 17: 50; 21: 23)

"To this end, we always pray for you, that our God may make you worthy of his calling and powerfully bring to fulfillment every good purpose and every effort of faith,
 that the name of our Lord Jesus may be glorified in you, and you in him,h in accord with the grace of our God and Lord Jesus Christ."  (2 Thessalonians 1: 11 - 12)