By him all that believe are justified from all things, from which ye could not be justified by the law of Moses– Acts 13:39
By him (Jesus Christ) all that believe are justified. To be justified means to be declared completely righteous, innocent before the law of God. It is as if you had never sinned at all.
The justification is by him. There is no other way to be found guiltless before a holy God. There is no way to live a good enough life to please a perfectly good God. Even a hundred good works cannot erase a single sin. But on the cross Christ took the sins of his people on himself, and gave them his righteousness. Therefore, his record is now their record, his perfection is their perfection.
As we are emphatically reminded, we could never be justified by the law of Moses; that perfect law only shows how imperfect we really are. But by Jesus Christ every person that believes is justified from all things.
You may have lived a corrupt and despicable life; or you may have lived a life which, to the rest of society, seemed good and acceptable. But neither is important in relation to your justification. Either way, only by him can you be justified; and either way, by him you can be justified. There is hope for anyone, but the only hope anyone has is in Christ.
There is no sin that cannot be cleaned by the blood of Christ; there is no life that cannot be justified by the cross of Christ. All that believe are justified from all things. Have you trusted in Jesus Christ for your justification?