“Adultery is always a mortal sin and the bishops who create confusion about this must study the doctrine of the Church,” Cardinal Gerhard Ludwig Müller, Prefect for the Congregation for the Doctrine of Faith, says in a new interview with the print journal Il Timone. “We have to help the sinner overcome sin and convert.”And, there's this from 2015:
The Ten Commandments are given to us by God. Have we any authority to say it is ‘unrealistic’ to expect people to keep any of the Ten Commandments, not only number six and number nine, also number five – abortion, killing of innocent people, number seven – stealing, whether small sums of money or big(.)
We cannot go on the reasoning that it is ‘unrealistic,’ he added. “You can say it is not easy. I accept that. Christ never promised us that it is easy to follow him. He said those who want to be his disciples must ‘take up their cross daily and follow me.’—Francis Cardinal Arinze
3. As I wrote in the Apostolic Exhortation Familiaris consortio, the divorced and remarried cannot be admitted to Eucharistic Communion since "their state and condition of life objectively contradict that union of love between Christ and the Church which is signified and effected by the Eucharist" (n. 84). And this is by virtue of the very authority of the Lord, Shepherd of Shepherds, who always seeks his sheep. It is also true with regard to Penance whose twofold yet single meaning of conversion and reconciliation is contradicted by the state of life of divorced and remarried couples who remain such.
However, there are many appropriate pastoral ways to help these people. The Church sees their suffering and the serious difficulties in which they live, and in her motherly love is concerned for them as well as for the children of their previous marriage: deprived of their birthright to the presence of both parents, they are the first victims of these painful events.