People sin. That much is directly stated in the holy scriptures. Some examples are in saint Paul's letters.
Rom 3:9-20 What then? are we better than they? No, in no wise: for we have before proved both Jews and Gentiles, that they are all under sin; (10) As it is written, There is none righteous, no, not one: (11) There is none that understandeth, there is none that seeketh after God. (12) They are all gone out of the way, they are together become unprofitable; there is none that doeth good, no, not one. (13) Their throat is an open sepulchre; with their tongues they have used deceit; the poison of asps is under their lips: (14) Whose mouth is full of cursing and bitterness: (15) Their feet are swift to shed blood: (16) Destruction and misery are in their ways: (17) And the way of peace have they not known: (18) There is no fear of God before their eyes. (19) Now we know that what things soever the law saith, it saith to them who are under the law: that every mouth may be stopped, and all the world may become guilty before God. (20) Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.
Rom 3:23* For all have sinned, and come short of the glory of God;
(Cambridge Bible)* Romans 3:23
all have sinned] Lit. all sinned: the Gr. aorist. Probably the time-reference of the tense is to the original Fall of Man, regarded as involving the individual experience of sinfulness in the case of each person. See however on Rom 1:19.
come short] A present tense. The result of the Fall is that they are now “short of the glory of God.” The word translated “come short” is translated “to be in want” (Luk 15:14); “to suffer need” (Php 4:12); “to be destitute” (Heb 11:37). Here the context suggests that modification of its root-meaning given in E. V.: “to suffer from defect,” “to fail to attain.”—“The glory of God” must here be His moral glory, His holiness and its requirements. In many passages the Word “glory” is used with evident reference to the Divine moral attributes—mercy, faithfulness, love—as well as to Divine power. See Rom 6:4; 2Co 4:4 (“the gospel of the glory of Christ”); Eph 1:12; Eph 1:14; 1Ti 1:11 (“the gospel of the glory of the blessed God”). Fallen man lies hopelessly below the standard of the spiritual law which is the expression of the essential holiness of God.