For example, lets say someone jaywalks across the street but before he does he thinks to himself well God will forgive me for this.
That statement
per se is not sinful: if one repents and fulfills the necessary conditions, God will indeed forgive him. In fact, God is always ready to forgive any sin. It is how this is expressed and felt in the soul that determines whether this motion of the spirit is sinful or not, and to what degree…ex. “before he does” hints to a sinful
intention, namely to do something wrong (which is indeed a venial sin!) and what is worse (and this
could be mortal sin, if there were grave matter, I guess
) justifying the doing something wrong based on God’s forgiveness - when in fact it is God’s explicit will that we never do evil, not even in order to obtain good (end does not justify means).
I know of someone who had a hard time, at one point, struggling with sins against the sixth commandment, because at the peak of temptation he’d always think: “anyways I can always go to Confession”. Now
that was a sin of presumption! For we don’t know the days of our life, or whether we will wake up in the morning, thus we ought to live every day as if it was the only day to serve the Lord. Just thought that this example with grave matter could help
)
From
here:
There are six sins that offend the Holy Spirit
(2) Presumption of God’s mercy
“There are two kinds of presumption. Either man presumes upon his own capacities, (hoping to be able to save himself without help from on high), or he presumes upon God’s almighty power or his mercy (hoping to obtain his forgiveness without conversion and glory without merit).” (C.C.C. # 2092)
On the other hand we can
count on God’s mercy to be
unconditional - that is, it would be on the other hand equally sinful to think that something we did is too terrible and that it is beyond God’s mercy - that would be sin (1) against the Holy Spirit: despair.
I think that the private revelations to S. Faustina of the Blessed Sacrament are currently the best way to understand the divine mercy of God. I include a few relevant quotes below. While such a private revelation does not constitute official Church teaching, it has been declared free from doctrinal and moral errors.
Tell souls not to place within their own hearts obstacles to My mercy, which so greatly wants to act within them. My mercy works in all those hearts which open their doors to it. Both the sinner and the righteous person have need of My mercy. Conversion, as well as perseverance, is a grace of My mercy.
I have opened my Heart as a living fountain of mercy. Let all souls draw life from it. Let them approach this sea of mercy with great trust.
Let the greatest sinners place their trust in My mercy. They have the right before others to trust in the abyss of My mercy. Souls that make an appeal to My mercy delight Me. To such souls I grant even more graces than they ask.
There is no misery that could be a match for My mercy, neither will misery exhaust it, because as it is being granted-it increases.
I received a deeper understanding of divine mercy. Only that soul who wants it will be damned, for God condemns no one.
I consider that the greatest difference is in the attitude: it is not the feeling of trust in God’s mercy - which should be infinite - but how we come to express that feeling: with arrogance (presumption) or with humbleness (consider the wonderful example of Luke 18:9-14).
