Not by works of any kind no matter how perfect

"Let me tell you, that the Lord hath so established Christ, for the rest and life of men, that if they could yield angelic obedience, be perfect throughout in obedience to the whole law of God, and not fail in one point of it; if, I say, from such perfection of obedience they would gather up their own comfort, or conclude their own salvation; these persons should be damned, as well as those that sin ever so much: for God hath established Christ, and only his righteousness, to be the salvation of man; I say, only the righteousness of Christ; that if a man were so perfect, and in respect of that perfection, would leave the righteousness of Christ, and lean to the perfection of his own, for his peace, and salvation; that man would miscarry, and be damned." -Tobias Crisp, Christ Alone Exalted, pg. 157


Martin Luther says in the Large Catechism found in the Book of Concords, "Therefore the Ten Commandments do not by themselves make us Christians, for God's wrath and displeasure still remain on us because we cannot fulfill his demands. But the Creed brings pure grace and makes us upright and pleasing to God." (Pg. 420)