Man himself is responsible for sin.

It is interesting to read the purification prayers of other religions. For example, the ancient Hindu supplication reads, “Purify, O God, my soul, see to its innocence! The evil spirit has deceived her; the flesh has deceived her… ”
How very differently Christianity explains sin and guilt! Origenes has calculated what all tempt us to sin: The world, i.e., the evil influences of the environment, the flesh, i.e., the sinful passions, the devil, who gives us evil thoughts, penetrating like arrows into our hearts. Who, then, is responsible for sin? But the answer is “Neither the world, nor the flesh, nor the devil!” God punished the devil for his sin. But for our sin, we bear the punishment ourselves because we alone are responsible for our willing consent to evil. Therefore, the only actual cause of sin
is our own will, which chooses evil. If the cause of sin were something other than ourselves, then the responsibility would fall on God Himself, who put us in this predicament.

The Christian, therefore, does not lay the blame on anyone or anything else; he beats his breast and says: “My fault!” Our purification prayers take this typical form: “God, have mercy on forgive me, forgive me, a sinner!” Transgression of God’s law Preachers uses analogy, a simile of moral and natural laws. Let’s build a house regardless of the laws of gravity, collapse it, and sow grain in the opposite season and in different climates; what will we reap? That is the result of even human life, which is contrary to the moral law given by God.
The simile itself is not bad. The good, which is eternal, is permanent and necessary; the necessity can then be expressed theoretically, expressed in law. They are thus natural laws of morality, of sound. Even in revealed religion, God has expressed His will in direction. Faithfulness to the Lord was judged among the Jews by how one kept the Law. Christ, the apostles, and the Church formulated their doctrine in certain principles. Christian morality collected them, sorted them out, classified them, and worked out a system. From time to time, however, the opposition is manifested to such a “legal morality,” where all sin} is as it were already pre-weighed. The Phariseeism that manifested itself at the end of the Old Testament is a sobering example of how the letter of the Law has replaced a personal, respectful relationship with God. The danger of Pharisaic then will always be alive, not in vain, is spoken of so many times in the Gospel. But it will not be eradicated by discarding and neglecting the Law. In a sense, the thought of St. Paul in his letter to Romans; the law is good and holy, but it is no substitute for Christ, and without him, it is meaningless.
But he who loves Christ keeps the commandments (Jn. 14, 15), thus expressing his love for him. Therefore, he is rightly afraid to break even the least of God’s commandments, lest he is the least in the kingdom of God (cf. Mt 5:19). According to St. Basil, the commandments of God shine like stars, according to which swimmers are guided at night not to lose their way. The alphabetical Psalm 118 has been figuratively called “the rosary of God’s law,” which is light and life for the one who walks without blemish “in the ways of the commandments.” For the Stoics, the moral law was an expression of the necessity of the world; for the Pharisees, it was a code of national duty and customs, but for the Christian, it must remain ever alive word of the heavenly Father, whom we daily assure:  Thy will be done! God’s insult.
Not only philosophers but also Catholic theologians have often had difficulty explaining expressions in Scripture and religious language: sin offends, grieves, anger, and therefore punishes God. Even St. Thomas Aquinas thinks that this can only be understood in a broader, figurative sense. Sin only harms us ourselves. I am not breaking the sun by boarding up the window, but I am depriving myself of its light. In dealing with people, we call the refusal of a gift an insult. Sin is the rejection of God’s love, the greatest gift, which is why we humanly call it “God’s insult,” even though it cannot touch God Himself. For it is eternally unchangeable happiness. However, such an explanation of the term does not quite satisfy spiritual authors. It seems to them too philosophical. Statements of Scripture and the saints would thereby lose their force and whole meaning. At understanding sin, we must not lose sight of the mystery of the Incarnation of the Son of God. He became a man. As a man, He endured pain and suffering. Sin made him accurate and complete…offended him. According to the Histological principle, then, the …that which is in Christ’s humanity is transferred to God. Right we say that God was born, suffered, died. God, therefore, sustained
insults for sin. The value of Christ’s life is eternal. It is not just something past. Furthermore, Christ lives on in His mystical body, the Church. There, too; therefore, he suffers, he dies. If we insult our neighbor, we insult Christ: whatever you have done to one of the least of these brothers of mine, you have done to me (Mt 25:40). In its more profound consequences, every sin, even solitary and private, offends our neighbors and, therefore, Christ and God. It is not, therefore, merely a distant figure of speech. We are touching on here the deepest mysteries of faith when we read, for example, the simple words of the devotion of the Stations of the Cross: ‘It was my sins that brought thee down to the ground, for they spat upon the divine face.