“The second thing is, how we may judge of our mortification.”
Those things which are not true mortification.
Merely reframing from some action: “All cessation from some particular sin is not a mortification. A non-commission of a particular sin is not an evidence of the mortification of the root of it. Indeed, a man cannot commit all kinds of sin at a time, nor in many years; the commands of sin are contrary, and many masters commanding contrary things cannot be served at one and the same time.”
One may give up only the outward display of the sin while maintaining the desire. Jesus explains that adultery and murder begin in the heart as unspoken lust and anger. They are still sin, even if not displayed.
Or one may cease to commit some particular sin for a number of reasons. Sometimes a sin is not committed because there is simply no opportunity to commit the sin. I would be thief, if only there were something to steal. “The pollutions of the world may be escaped when the pollutions of the heart remain.”
Some sins we cannot commit because our body will not cooperate with the sin. (It was once explained to me that one reason for jail for violent crime is that kept a young man out of service until he became too old to engage in such crimes.) “A present sickness may make an epicure nauseate the dainties which he would before rake even in the sea to procure. There is a cessation from acts of sin, not out of a sense of sin, but a change of the temper of his body.”
Sometimes a flood of guilt or shame keeps one off from a particular sin for some time, but when the guilt subsides and the opportunity returns, so does the sin.
And finally, one may just trade one sin for other. “A cessation from one sin may be but an exchange.” Certain sins are mutually exclusive: you cannot be profligate and a miser at the same time.
Being prevented from engaging in a sin: “Restraints from sin are not mortification of it. Men may be curbed when they are not changed; and there is no man in the world but God doth restrain him from more sins, which he hath a nature to commit, than what he doth actually commit.”
Why is a restraint not mortification? Restraints do not get to the heart.
“Mortification is always from an inward principle in the heart, restraints from an outward.” True mortification will not be merely refraining from some action, but also a desire to refrain. “In a renewed man, there is something beside bare considerations to withhold him, something of antipathy which heightens and improves those considerations, whereby the soul is glad of them, because the edge and dint of them is against sin.”
In true mortification, one does not refrain from the sin because it is too hard to commit; one refrains from the sin because there is a “hatred of sin”. “[M]ortification proceeds from an anger, a desire of revenge.”
Sin is not the bare action: the law distinguished between an accidental killing a deliberate murder: the intent made the thing a sin. Thus, mortification is not merely the outward restraint but a change in the thought and affection, “Mortification is a voluntary, rational work of the soul; restraints are not so. The devil hath nothing of his nature altered, but hath as strong an inclination to sin as ever, though the act he intends is often hindered by God.”