Without salvation, your life is bound to the letter of the law. Without a functional spiritual life, your life is bound to the letter of the law. Without the work of Christ, you have no way out from under the letter of the law, and therefore your destiny would be only eternal condemnation, or something that would be impossible for you to free yourself from.
But with the work of Christ, which paid for all the costs of death and sin, we are now free, by means of faith, from the chains of the law.
And now that we are free, it would not make sense to try to return to the human works pattern described by the law, when we have so much more by means of grace.
Therefore, it would only make sense that given a new life, a person would work within the scope of that new life, rather than return to the old habits of the scope of the old life of the sin nature.
Unfortunately, too many people are too lazy, or to indifferent, or simply not interested in the mandates of grace, because they are blocked by their own self-induced arrogance, which prevents them from listening and learning and advancing in their spiritual life.
It is far easier to get caught up in the emotion, and the clichés, and the entertaining aspects of Christianity, and end up with nothing, than it is to knuckle down and learn Bible doctrine, word by word, verse by verse, precept by precept, in order to advance to something more.