In as much as sin is an action yes. Sometimes we choose actions which are not sins. In so far a sin is a state of corruption, we are always partially corrupt, but not completely so. God put some good in us. Certainly all that is good comes from God, but hey we came from God. He created us. What is more He created us in his own image.
I’ve had this discussion with the “Calvinist swarm” before. And we’re not so far apart (Catholics and Calvinists) on the issue of free will, but it’s the issue of total depravity which causes a difference.
Both Catholics and Calvinists believe mankind is utterly incapable of his own salvation, and that even the desire for salvation is a grace given to him by God. Catholics tend to define unredeemed man as a slave to sin, while the redeemed man has been liberated. Calvinists see the unredeemed man as freely choosing wickedness, but then becoming a servant of Christ. Both perspectives, however, are completely apt, and used many times in the bible, including by the same people, such as Paul.
The question is: what is man’s will? Which experience of man properly defines “free will” or “servitude”? And the reason that Catholics and Calvinists answer this differently is because of the notion of total depravity. Simply put, Calvinists believe that every action by every unredeemed person is intrinsically evil. If God uses an unredeemed person, it is by trickery. Catholics hold that even as-yet unredeemed people can have a marginal amount of grace, which can inspire them to do draw near to God, in spite of competing sinful inclinations. Of course, even these distinctions are a matter of perspective, since Calvinists recognize that God can put order the cosmos so as to lead people to himself, and even Catholics recognize that ultimately, any good work which does not result in salvation is intrinsically futile, and thus, not really a good work.
I can think of at several doctrines which explain these opposing perspectives. One is the efficacy of sacraments. A hyper-Lutheran notion of faith alone holds counts sacraments as works. Only faith saves, the notion goes, but how does one get faith? Catholics hold that sacraments draw people towards further grace once receiving slight amounts of faith through prevening grace. Many Calvinists would hold any unredeemed person involving themselves in ritual is just vainly trying to save themselves.
Another doctrine is the purity of Mary. Calvinists hold that Mary became redeemed after committing sins. Thus, she fits the model of having been totally depraved prior to receiving irresistable grace. Catholics hold that having been untouched by original sin, Mary’s statement, “Let it be done unto me according to thine will” is a statement of her free will, which could not possibly choose goodness if she were absolutely depraved. Yet she stated this before encountering Christ in his own conception within her. And thus, a radically different notion of original sin emerges: Mankind was capable of rejecting the fruit in the garden, for all though Eve chose evil, the new Eve rejects evil (where the English text has Jesus calling Mary “woman,” in Aramaic, this word would have been “Eve”.)