OBVIOUSLY the gift is FAITH - seems to be in the Form of Holy Spirit CONVICTION of SIN and of Judgement. Obviously Without FAITH (which is impossible for humans to generate), and repentance (only possible under Conviction of SIN) salvation is impossible.
Obviously it was not obvious to
“8. For by grace (tēi gar chariti). Explanatory reason. “By the grace” already mentioned in verse 5 and so with the article. Through faith (dia pisteōs). This phrase he adds in repeating what he said in verse 5 to make it plainer. “Grace” is God’s part, “faith” ours. And that (kai touto). Neuter, not feminine tautē, and so refers not to pistis (feminine) or to charis (feminine also), but to the act of being saved by grace conditioned on faith on our part. Paul shows that salvation does not have its source (ex humōn, out of you) in men, but from God. Besides, it is God’s gift (dōron) and not the result of our work.”
(A. T. Robertson, Word Pictures in the New Testament, Accordance electronic ed. (Altamonte Springs: OakTree Software, 2001), paragraph 5313.)
“8. For by grace, etc. This may truly be called exceeding riches of grace, for ye are saved by grace. Grace has the article, the grace of God, in vers. 5, 7.
And that. Not faith, but the salvation.”
(Marvin R. Vincent, Word Studies in the New Testament, Accordance electronic ed. (2004), paragraph 14955.)
“But whether are we to understand, faith or salvation as being the gift of God? This question is answered by the Greek text: τη γαρ χαριτι εστε σεσωσμενοι δια της πιστεως· και τουτο ουκ εξ υμων· θεου το δωρον, ουκ εξ εργων· ινα μη τις καυχησηται? “By this grace ye are saved through faith; and THIS (τουτο, this salvation) not of you; it is the gift of God, not of works: so that no one can boast.” “The relative τουτο, this, which is in the neuter gender, cannot stand for πιστις, faith, which is the feminine; but it has the whole sentence that goes before for its antecedent.””
(Adam Clarke, Adam Clarke’s Commentary on the Whole Bible, Accordance electronic ed. (Altamonte Springs: OakTree Software, 2004), paragraph 47787.)
“And that not of yourselves. That is, salvation does not proceed from yourselves. The word rendered that—τουτο—is in the neuter gender, and the word faith—πιστις—is in the feminine. The word “that,” therefore, does not refer particularly to faith, as being the gift of God, but to the salvation by grace of which he had been speaking. This is the interpretation of the passage which is the most obvious, and which is now generally conceded to be the true one.”
(Albert Barnes, Barnes’ Notes on the New Testament, Accordance electronic ed. (Altamonte Springs: OakTree Software, 2006), paragraph 23010.)