He that walketh uprightly (Proverbs 2:7); Vulgate and Septuagint, "in simplicity," having nothing to conceal or to fear. So Christ enjoins his followers to be guileless as children, and harmless as doves.
Surely; equivalent to "securely;" ἀμερίμνως, Aquila, having no fear of inopportune exposure, because he has no secret sin. He that perverteth his ways; deals in crooked practices. Shall be known (Proverbs 12:16).
He shall be exposed and punished, and put to open shame. Having this apprehension always present, he cannot walk with confidence as the innocent does. Hence the antithesis in the text.