Charles H. Spurgeon on Psalms 15:2

"He that walketh uprightly," etc. If neither the golden reason of excellency can move us, nor the silver reason of profit allure us, then must the iron reason of necessity enforce us to integrity and uprightness of heart. For first, such is the necessity thereof, that without integrity the best graces we seem to have are counterfeit, and, therefore, but glorious sins; the best worship we can perform is but hypocrisy, and therefore abominable in God's sight. For uprightness is the soundness of all grace and virtues, as also of all religion and worship of God, without which they are unsound and nothing worth. And first, as touching graces, if they be not joined with uprightness of heart, they are sins under the masks or vizards of virtue, yea, as it may seem, double sins: for as Augustine saith, Simulata aequitas est duplex iniquitas, quia et inquitas est, et similatio: Feigned equity is double iniquity, both because it is iniquity, and because it is feigning. George Downame, D.D., 1604.