From the Epistle to the Ephesians
To the Ephesians he addresses words of the same import: “And you when you were dead in trespasses and sins; wherein in time past you walked according to the course of this world according to the prince of the power of the air, the spirit of him that now works in the children of disobedience; among whom also we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others.
But God, who is rich in mercy, for His great love wherewith He loved us, even when we were dead in sins, has quickened us together with Christ; by whose grace you are saved.” Again, a little afterwards, he says: “By grace are you saved through faith; and that not of yourselves: it is the gift of God: not of works, lest any man should boast. For we are His workmanship, created in Christ Jesus unto good works, which God has before ordained that we should walk in them.” And again, after a short interval: “At that time you were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world: but now, in Christ Jesus, you who were sometimes far off are made near by the blood of Christ.
For He is our peace, who has made both one, and has broken down the middle wall of partition between us; having abolished in His flesh the enmity, even the law of commandments contained in ordinances; for to make in Himself of two one new man, so making peace; and that He might reconcile both unto God in one body by the cross, having in Himself slain the enmity; and He came and preached peace to you which were afar off, and to them that were near. For through Him we both have access by one Spirit unto the Father.” Then in another passage he thus writes: “As the truth is in Jesus: that you put off, concerning the former conversation, the old man, which is corrupt according to the deceitful lusts; and be renewed in the spirit of your mind; and that you put on the new man, which after God is created in righteousness and true holiness.” And again: “Grieve not the Holy Spirit of God, whereby you are sealed unto the day of redemption.”
Source: Merits and Remission of Sin, and Infant Baptism (New Advent)