Nothing has changed. Pope Francis has not declared that an issue of grave matter is no longer grave matter. The Moral Law still stands unchanged and nothing challenged. What can be forgotten is that for mortal sin to exist, grave matter must be accompanied at the same time by full knowledge and full consent. Full knowledge and full consent is a situational and personal matter for discernment and it has always asked discernment. Nothing has changed.
Too often have we Catholics stated that something in the Moral Law is a mortal sin when the fact is that it is grave matter only - with the potential only to be mortal sin and dependant on two other conditions.
Nothing has changed.
What is refreshing and very welcome since AL is that Pope Francis has probably (at last!) all levels in The Church discussing what is and is not mortal sin i.e. discussing full knowledge and full consent and the relationship to morally grave matter i.e. when and when not morally grave matter is or is not mortal sin.
Something has changed and it needed to change.
Catholic Catechism: “Sin”
http://www.vatican.va/archive/ccc_css/archive/catechism/p3s1c1a8.htm
1859 Mortal sin requires full knowledge and complete consent. It presupposes knowledge of the sinful character of the act, of its opposition to God’s law. It also implies a consent sufficiently deliberate to be a personal choice. Feigned ignorance and hardness of heart133 do not diminish, but rather increase, the voluntary character of a sin.
1860 Unintentional ignorance can diminish or even remove the imputability of a grave offense. But no one is deemed to be ignorant of the principles of the moral law, which are written in the conscience of every man. The promptings of feelings and passions can also diminish the voluntary and free character of the offense, as can external pressures or pathological disorders. Sin committed through malice, by deliberate choice of evil, is the gravest.
1861 Mortal sin is a radical possibility of human freedom, as is love itself. It results in the loss of charity and the privation of sanctifying grace, that is, of the state of grace. If it is not redeemed by repentance and God’s forgiveness, it causes exclusion from Christ’s kingdom and the eternal death of hell, for our freedom has the power to make choices for ever, with no turning back. However, although we can judge that an act is in itself a grave offense, we must entrust judgment of persons to the justice and mercy of God.
1862 One commits venial sin when, in a less serious matter, he does not observe the standard prescribed by the moral law, or when he disobeys the moral law in a grave matter, but without full knowledge or without complete consent.