Question: Is it possible for God to refuse to forgive a sinner?
Answer: Yes, God can. But No, He does not.
The answer is a little complicated because it depends on how you view it. If you mean whether God can say no to a sincerely repentant sinner, the answer is always no. No matter how many times the person has fallen and come back, God always says yes.
Remember the parable of the Prodigal Son? The Father’s forgiveness wasn’t simply restorative but was elevational. The sinner wasn’t merely restored to their previous state but was elevated because of the sincerity of their repentance. The son never lost his place as a son in reality. He once reduced himself to a swine and fed with them. But when he rediscovered his identity as a son, he forgave himself and sought his father.
His father remained his father to him even while in exile; he remembers his own identity as son and said, “I shall arise and return to my father.” Luke 15.
Once he made an effort, the father did the rest by running toward him.
His father also ignored his plea, showing that his forgiveness is always available to the son whenever he forgives himself and seeks forgiveness from his father. In a way, his father’s forgiveness was a “constant.” The only movement necessary to gain this forgiveness was that of his son.
This parable is deep and profound and illustrates how God himself forgives his children. The child must first forgive himself, humble himself, and seek out his father. Once that effort is made, the Father ALWAYS forgives.
The Sacrifice of Jesus and the institution of the Sacraments are many ways God has made sure that his mercy is abundant to us, so in this way, God can NEVER turn away a penitent who seeks him.
However, when considered differently, it might look like God can reject a sinner. But in reality, it is the sinner who rejects the mercy of God. Either by refusing to forgive himself and seeing how much God loves him. Or by betraying the mercy of God by planning his sins around his mercy.
No matter the sin, forgive yourself enough to seek the mercy of God, and you can be absolutely sure that God will never turn away a sincerely repentant sinner.