The above is said at the end of the Penitential Rite, soon after Mass begins. A Lutheran acquaintance complained a few weeks back about the said prayer because it says "may" when it is already a fact that God has shown mercy and forgiven our sins. This is a common understanding among Protestants for whom it is most important to emphasize that we have obtained forgiveness unmerited -- past, present and future. However, while it is true that the once and for all atonement in Calvary expiates all our sins for all times, it remains a proper posture for us to actually ask for forgiveness at all times. Protestants variably refer to this as being confronted by the Law and living out repentance for our entire lives, or, as some Evangelicals use the term, pleading the blood for forgiveness (among other things). None of them would deny the singular event on Calvary, but they mostly recognize that we all continue to sin, even after having become Christians (whether from baptism or, as others think, from praying the sinner's prayer). For these, which were not confessed when we first became Christians, we humbly ask pardon. And for our continuing attachment to sin -- concupiscence -- leading us to the same sin again and again, we must repent.
Therefore, I don't see that the above prayer is problematic at all. It would not have met with objections if ancient Christian liturgy and Scriptures are any indication. Here is an ancient Lenten prayer, which is also a commentary for today's Gospel reading (Luke 15:1 - 32) on the prodigal son:
Saint Andrew of Crete (660-740), monk and Bishop|
Grand canon of the Orthodox Lenten liturgy, 1st ode
"Here am I, dying from hunger. I shall get up and go to my father"
How shall I begin to weep for the works of my life?
What shall be the first notes of my mourning chant?
In your mercy, O Christ, grant me the forgiveness of my sins…
As the potter who moulds the clay
So you have given me, O my Creator, flesh and bones, breath and life.
O Lord who created me, my judge and Saviour,
Take me back to you this day.
O my Saviour, before you I confess my sins.
I have fallen beneath the blows of the Adversary;
Behold the wounds with which my death-dealing thoughts
Have wounded, like brigands, my soul and body (Lk 10,30f.).
I have sinned, my Lord, yet I know that you love mankind.
It is in tenderness you chastise us
And in your ardent compassion.
You see me weeping and come towards me
Like the Father welcoming the prodigal son.
Since my youth, O my Saviour, I have despised your commandments.
I have spent my life in obsession and heedlessness.
I call to you: Before I die,
I have dissipated in emptiness the inheritance of my soul.
I lack the fruits of fervour and now I feel hunger.
I cry out: Father, full of compassion, come to me,
Take me in your mercy.
The one whom the robbers attacked (Lk 10,30f.)
Is myself in the midst of the wandering of my thoughts.
They strike me and wound me.
But you, O Christ my Saviour, bend down to me and heal me.
The priest sees me and turns away.
The Levite sees me, naked and in distress, but passes by on the other side.
But you, O Jesus born of Mary,
You stop to help me.
Jesus, I cast myself at your feet;
I have sinned against your love.
Free me from this burden for it is too heavy for me
And, in your mercy, take me to yourself.
Do not enter into judgement with me,
Do not uncover my deeds,
Nor inspect my motives and desires.
But in your compassion, All-Powerful one,
Close your eyes to my sins and save me.
Now is the time of repentance. I come to you.
Free me from the heavy burden of my sins
And, in your gentleness, grant to me tears of repentance.