God gives us the fullness of His grace at baptism; it remains in us, but does not force itself on us. Respectful of our freedom, God does not compel us to experience the effects of grace. Man is perfectly purified through baptism, but he remains free to sin–and if he does sin, he defiles himself as before. It is thus necessary that man fight so as not to turn back and fall again into sin and the passions….
Full freedom lies at our disposal and the sins we commit after baptism are due only to the misuse of this freedom. We continue to be tempted after baptism–we cannot prevent this, since it comes from the devil and we are in no way responsible for it. But it is our responsibility to reject these suggestions. We are totally free when faced with temptation; baptism has given us the power to resist the tempter victoriously.
Nothing of what we reject can harm or abide in us. If we assent to the temptations, it is because we really want to do so and we do so in complete freedom.
~Dr Jean-Claude Larchet (Therapy of Spiritual Illnesses vol.2 pp.58-59)
Prayerful Life 