The doors are open for all who sincerely and wholeheartedly return to God; indeed, the Father is most willing to welcome back a truly repentant son or daughter. The result of true repentance, however, is that you do not fall into the same faults again, but utterly uproot from your souls the sins for which you consider yourself worthy of death.
When these have been destroyed God will again dwell within you, since Scripture says that for the Father and his angels in heaven the festal joy and gladness at the return of one repentant sinner is great beyond compare. That is why the Lord cried out:
What I want is mercy, not sacrifice. I desire not the death of a sinner but his conversion. Even if your sins are like crimson wool I will make them as white as snow; even if they are blacker than night I will wash them as white as wool. (Ez 18:23)
You must also curb all the other evil passions: anger, lust, grief, and fear. Although only God has power to forgive sins and cancel transgressions, the Lord commands us also to forgive our repentant brothers and sisters every day.
So if we who are evil know how to give good gifts, how much more generous must be the Father of mercies, the good Father of all consolation, who is full of compassion and mercy, and whose nature it is to be patient and await our conversion!
Genuine conversion, however, means ceasing to sin without any backward glances.
God pardons what is past, then, but for the future we are each responsible for ourselves. By repenting we condemn our past misdeeds and beg forgiveness of the Father, the only one who can in his mercy undo what has been done, and wipe away our past sins with the dew of his Spirit.
And so, if you are a thief and desire to be forgiven, steal no more. If you are a robber, return your gains with interest. If you have been a false witness, practice speaking the truth. If you are a perjurer, stop taking oaths. You must also curb all the other evil passions: anger, lust, grief, and fear.
No doubt you will be unable all at once to root out passions habitually given way to, but this can be achieved by God’s power, human prayers, the help of your brothers and sisters, sincere repentance, and constant practice.
St Clement of Alexandria