Faith

In faith is assurance of assent, whereby the man assuredly believes whatever God has said in His Word to be true; and that not upon the testimony of men, or ministers or angels, but upon the testimony and authority of the God of truth, for whom it is impossible to lie, speaking in his own Word, and saying, Thus saith the Lord. But in a particular manner the soul gives its assent unto the truth of the Gospel, and the revelation of the Word, concerning the persons, natures, offices, undertakings and performances of our Lord Jesus Christ, as the Redeemer, Surety, and Saviour, of lost sinners. The man's understanding being enlightened with the knowledge of Christ, and having got a view of him by the Spirit of wisdom and revelation, he finds it to be all true that God has said of Christ in the Word; so that he cannot shun, in this case, to join issue with the apostle, "This is indeed a faithful saying, That Christ Jesus came into the world to save sinners." –1 Tim i. 15. He sees the truth and veracity of God so much engaged in the covenant and promises thereof, that they are more firm than the everlasting mountains and perpetual hills. –Isa. liv. 10. Now, this certainty of assent is, in Scripture dialect, called a "believing the report of the Gospel,"–Isa. liii. 1; a "receiving the record of God,"–1 John v. 10-11; a "setting to the seal that God is true," –John iii.33.
—Ebenezer Erskine "The Assurance of Faith Opened and Applied."