Practice makes perfect for well or ill. We’re either making ourselves better or making ourselves worse, and what we make habits of the soul will lead us to inevitable destinations.
We become that which we love in our hearts, “for as a man thinks in his heart, that is what he is”.
This has a lot to do with the training and shaping of a Christian conscience; what a Christian will find disgusting and unacceptable can be changed through ongoing exposure to and accommodation toward injustice, fleshly indulgence, unchaste thoughts, immoderate humor, etc. Purity is one with responsibility not because we do not have Christian Liberty, but because we do.
Contrary to much contemporary Christian thought on the matter, Christian Liberty is not the justification for the Christian to practice myriad evils without the nagging weight of conscience, it is being free from the dictates of mere human judgement in regard to arguable matters. Christian Liberty says yes to all that God says yes. Fleshly indulgence says yes to all that shares its passions. The laws of God are the only arbiter in these matters.
As R. C. Sproul writes on this: “The tragedy of the contemporary evangelical church is its failure to know and establish the law of God.”
For example, The Wesminster Large Catechism in its judgment upon what thoughts and actions are obedient to the law of God within the bounds of Christian liberty says this:
Q. 135. What are the duties required in the sixth commandment?
A. The duties required in the sixth commandment are, all careful studies, and lawful endeavors, to preserve the life of ourselves and others by resisting all thoughts and purposes, subduing all passions, and avoiding all occasions, temptations, and practices, which tend to the unjust taking away the life of any; by just defense thereof against violence, patient bearing of the hand of God, quietness of mind, cheerfulness of spirit; a sober use of meat, drink, physic, sleep, labor, and recreations; by charitable thoughts, love, compassion, meekness, gentleness, kindness; peaceable, mild and courteous speeches and behavior; forbearance, readiness to be reconciled, patient bearing and forgiving of injuries, and requiting good for evil; comforting and succoring the distressed, and protecting and defending the innocent.
And on how we break the law of God under Christian Liberty, this:
Q. 136. What are the sins forbidden in the sixth commandment?
A. The sins forbidden in the sixth commandment are, all taking away the life of ourselves, or of others, except in case of public justice, lawful war, or necessary defense; the neglecting or withdrawing the lawful and necessary means of preservation of life; sinful anger, hatred, envy, desire of revenge; all excessive passions, distracting cares; immoderate use of meat, drink, labor, and recreations; provoking words, oppression, quarreling, striking, wounding, and whatsoever else tends to the destruction of the life of any.
The laws of God are the ethical expression of the nature of God as a personal being involved in the faith and life of His Church. Far from their being something irrelevant to contemporary Christian faith and practice, they are contemporary Christian faith and practice.