My Summary of Christian Doctrine: The Veracity, truthfulness and faithfulness of God.

Num 23:19  God is not a man that He should lie, neither the son of man that He should repent. Has He said, and shall He not do it? Or has He spoken, and shall He not make it good?

2Ti 2:13  If we do not believe Him, yet He remains faithful; He cannot deny Himself.

What do we include in the Veracity of God?

God is always true in His Inner Being, in His Revelation, and in His relation to His people.

He is the True and Living God, over against the idols of man. He knows all things as they really are, and is always faithful to fulfill all His promises. So this Attribute can also be called the Faithfulness of God. L.B. p.37

1Co 1:9  God is ever true to His promises, and it was by Him that you were, one and all, called into fellowship with his Son Jesus Christ, our Lord.

God is faithful - That is, God is true, and constant, and will adhere to his promises. He will not deceive. He will not promise, and then fail to perform; he will not commence anything which he will not perfect and finish. The object of Paul in introducing the idea of the faithfulness of God here, is to show the reason for believing that the Christians at Corinth would be kept unto everlasting life. The evidence that they will persevere depends on the fidelity of God; and the argument of the apostle is, that as they had been called by Him into the fellowship of his Son, his faithfulness of character would render it certain that they would be kept to eternal life. The same idea he has presented in Phi_1:6, “Being confident of this very thing, that he which hath begun a good work in you, will also perform it until the day of Jesus Christ.” Barnes Notes

Faithful – Constant in the performance of duties; true to one’s word; one who is worthy of trust; one who can be counted on, firm to adherence to promises, steadfast in affection or allegiance, loyal. Charisfamily.org

2Ti 2:13  "And even if *our* faith fails, He remains true--He cannot prove false to Himself."

True: G4103 πιστός pistos Thayer Definition:

1) trusty, faithful 1a) of persons who show themselves faithful in the transaction of business, the execution of commands, or the discharge of official duties 1b) one who kept his plighted faith, worthy of trust 1c) that can be relied on

2) easily persuaded 2a) believing, confiding, trusting 2b) in the NT one who trusts in God’s promises 2b1) one who is convinced that Jesus has been raised from the dead 2b2) one who has become convinced that Jesus is the Messiah and author of salvation

Part of Speech: adjective

GOD IS TRUSTWORTHY

Heb 10:23  We must hold tightly to the hope that we say is ours. After all, we can trust the one who made the agreement with us.

Notes

For He is faithful that promised - To induce them to hold fast their profession, the apostle adds this additional consideration. God, who had promised eternal life to them, was faithful to all that he had said. The argument here is:

(1) that since God is so faithful to us, we ought to be faithful to him;

(2) the fact that he is faithful is an encouragement to us.

We are dependent on him for grace to hold fast our profession. If he were to prove unfaithful, we should have no strength to do it. But this he never does; and we may be assured, that all that he has promised he will perform. To the service of such a God, therefore, we should adhere without wavering; compare the notes on 1Co_10:13. Barnes Notes