Belief of the Truth of the Gospel is the result of the sanctifying work of the Spirit 2 Thess 2:13
But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth:
Amen! All those Chosen in Christ their Surety, who were blessed with all Spiritual Blessings Eph. 1:3-4, were also Sanctified by His Death for them.
Heb. 10:10, 14
10 By the which will we are sanctified through the offering of the body of Jesus Christ once for all. 14
For by one offering he hath perfected for ever them that are sanctified.
They shall be given New Birth, being
Sanctified by the Spirit internally, a continual on-going action Phil. 1:6; 2 Pet. 3:18, which He performs in each one of them
resulting in their Belief of the Truth John 14:6.
Titus 1:1-2
1 Paul, a servant of God, and an apostle of Jesus Christ, according to t
he faith of God's elect, and
the acknowledging of the truth which is after godliness; 2 In hope of eternal life, which God, that cannot lie, promised before the world began;
