Praying for the Spirit

And in order that we may come to Christ, the Holy Ghost works true faith through the hearing of the Word, as the apostle testifies when he says, Rom. 10:17: Faith cometh by hearing and hearing by the Word of God, [namely] when it is preached in its truth and purity. Therefore, whoever would be saved should not trouble or harass himself with thoughts concerning the secret counsel of God, as to whether he also is elected and ordained to eternal life, with which miserable Satan usually attacks and annoys godly hearts. But they should hear Christ [and look upon Him as the Book of Life in which is written the eternal election], who is the Book of Life and of God’s eternal election of all of God’s children to eternal life: He testifies to all men without distinction that it is God’s will that all men should come to Him who labor and are heavy laden with sin, in order that He may give them rest and save them, Matt. 11:28. According to this doctrine of His they should abstain from their sins, repent, believe His promise, and entirely trust in Him; and since we cannot do this by ourselves, of our own powers, the Holy Ghost desires to work these things, namely, repentance and faith, in us through the Word and Sacraments. And in order that we may attain this, persevere in it, and remain steadfast, we should implore God for His grace, which He has promised us in Holy Baptism, and, no doubt, He will impart it to us according to His promise, as He has said, Luke 11:11ff : If a son shall ask bread of any of you that is a father, will he give him a stone? Or if he ask a fish, will he for a fish give him a serpent? Or if he shall ask an egg, will he offer him a scorpion? If ye, then, being evil, know how to give good gifts unto your children, how much more shall your heavenly Father give the Holy Spirit to them that ask Him!
Formula Of Concord, Solid Declaration, Article XI, Paragraphs 69-71