A bit of the Book of Concord which I think shed a fair amount of light on what we mean by free will as it pertains to our salvation.
For, as Doctor Luther says Ps. 90: “In worldly and external affairs; which pertain to the livelihood and maintenance of the body, man is cunning, intelligent, and quite active; but in spiritual and divine things, which pertain to the salvation of the soul, man is like a pillar of salt, like Lot’s wife, yea, like a log and a stone, like a lifeless statue, which uses neither eyes nor mouth, neither sense nor heart.
21] For man neither sees nor perceives the terrible and fierce wrath of God on account of sin and death [resulting from it], but ever continues in his security, even knowingly and willingly, and thereby falls into a thousand dangers, and finally into eternal death and damnation; and no prayers, no supplications, no admonitions, yea, also no threats, no chiding, are of any avail, yea, all teaching and preaching is lost upon him, until he is enlightened, converted, and regenerated by the Holy Ghost,
22] for which [renewal of the Holy Ghost], indeed, no stone or block, but man alone, was created. And although God, according to His just, strict sentence, has utterly cast away the fallen evil spirits forever, He has nevertheless, out of special, pure mercy, willed that poor fallen human nature might again become and be capable and participant of conversion, the grace of God and eternal life; not from its own natural, active [or effective] skill, aptness, or capacity (for the nature of man is obstinate enmity against God), but from pure grace, through the gracious efficacious working of the Holy Ghost.”
23] And this Dr. Luther calls capacitatem (non activam, sed passivam), which he explains thus: Quando patres liberum arbitrium defendunt, capacitatem liberatatis eius praedicant, quod scilicet verti potest ad bonum per gratiam Dei et fieri revera liberum, ad quod creatum est. That is: When the Fathers defend the free will, they are speaking of this, that it is capable of freedom in this sense, that by God’s grace it can be converted to good, and become truly free, for which it was created in the beginning. (Tom. 1, p. 236.) To like effect also Augustine has written, lib. 2, Contra Iulianum. Doctor Luther on Hosea 6; also in the Church-Postil on the Epistle for Christmas; also on the Gospel for the third Sunday after Epiphany.
24] But before man is enlightened, converted, regenerated, renewed, and drawn by the Holy Ghost, he can of himself and of his own natural powers begin, work, or concur in working in spiritual things and in his own conversion or regeneration just as little as a stone or a block or clay. For although he can control the outward members and hear the Gospel, and to a certain extent meditate upon it, also discourse concerning it, as is to be seen in the Pharisees and hypocrites, nevertheless he regards it as foolishness, and cannot believe it. And in this respect he acts even worse than a block, inasmuch as he is rebellious and hostile to God’s will, unless the Holy Ghost is efficacious in him, and kindles and works in him faith and other virtues pleasing to God, and obedience.
25] Thirdly, in this manner, too, the Holy Scriptures ascribe conversion, faith in Christ, regeneration, renewal, and all that belongs to their efficacious beginning and completion, not to the human powers of the natural free will, neither entirely nor half, nor in any, even the least or most inconsiderable part, but in solidum, that is, entirely, solely, to the divine working and the Holy Ghost, as also the Apology teaches.
26] Reason and free will are able to a certain extent to live an outwardly decent life; but to be born anew, and to obtain inwardly another heart, mind, and disposition, this only the Holy Ghost effects. He opens the understanding and heart to understand the Scriptures and to give heed to the Word, as it is written Luke 24:45: Then opened He their understanding that they might understand the Scriptures. Also Acts 16:14: Lydia heard us; whose heart the Lord opened that she attended unto the things which were spoken of Paul. He worketh in us both to will and to do of His own good pleasure, Phil. 2:13. He gives repentance, Acts 5:31; 2 Tim. 2:25. He works faith, Phil. 1:29: For unto you it is given, in behalf of Christ, not only to believe on Him. Eph. 2:8: It is the gift of God. John 6:29: This is the work of God, that ye believe on Him whom He hath sent. He gives an understanding heart, seeing eyes, and hearing ears, Deut. 29:4; Matt. 13:15. He is a Spirit of regeneration and renewal, Titus 3:5. 6. He takes away the hard heart of stone, and gives a new tender heart of flesh, that we may walk in His commands, Ezek. 11:19; Deut. 30:6; Ps. 51:10. He creates us in Christ Jesus to good works, Eph. 2:10, and makes us new creatures, 2 Cor. 5:17; Gal. 6:15. And, in short, Every good gift is of God, Jas. 1:17. No one can come to Christ unless the Father draw him, John 6:44. No one knoweth the Father, save him to whom the Son will reveal Him, Matt. 11:27. No one can call Christ Lord except by the Holy Ghost, 1 Cor. 12:3. Without Me, says Christ, ye can do nothing, John 15:5. All our sufficiency is of God, 2 Cor. 3:5. What hast thou that thou didst not receive? Now, if thou didst receive it, why dost thou glory as if thou hadst not received it? 1 Cor. 4:7.
27] Accordingly, St. Augustine particularly writes of this passage that by it he was convinced that he must lay aside his former erroneous opinion, when he had maintained the following in his treatise De Praedestinatione, chap. 3: Gratiam Dei in eo tantum consistere, quod in praeconio veritatis Dei voluntas nobis revelaretur; ut autem praedicato nobis evangelio consentiremus, nostrum esse proprium et ex nobis esse. Item erravi (inquit), cum dicerem, nostrum esse credere et velle; Dei autem, dare credentibus et volentibus facultatem operandi. That is: I erred in this, that I held that the grace of God consists only in this, that God in the preaching of the truth reveals His will; but that our consenting to the preached Gospel is our own work, and is within our own powers. Likewise, St. Augustine writes further: I erred when I said that it is within our own power to believe the Gospel and to will; but it is God’s work to give to them that believe and will the power to effect something.
28] This doctrine is founded upon God’s Word, and conformable to the Augsburg Confession and other writings above mentioned, […]
And yes, if you read this carelessly, one can see where the one shot conversion that some evangelicals proclaim, but Luther always proclaimed and lived that you had to live every day (as much as you could), in the Lord. It’s not a ‘One and Done’,. It never was.