The apostle James explained our comprehensive accountability to God in his letter.
For whoever keeps the whole law but fails in one point has become accountable for all of it. (James 2:10).
Of course this affects our confession of sin since, even if we’re doing every other part of the law but we find one sin, then we must admit complete guilt. If a man dies of a heart attack, it doesn’t mean he died in every way he possibly could. One way of death is enough to make a man completely dead. Likewise, one sin is enough to make us accountable for all of the law.
Remember the context in which James gives this explanation. Consider what he had in mind when he said “fails in one point.” While the application follows for many sins, the sin James was addressing was a failure to “fulfill the royal law according to the Scripture.” James was confronting the sin of partiality (in the church) since the start of chapter two. The royal law violated was, “You shall love your neighbor as yourself.”
If we obey everything else in the law but neighbor-loving (which is unlikely, but go with the argument), then we are fully disobedient. Why? Because the law requires love. The law requires love because God is triune. The triune God made us for relationships, with Himself and with each other. That’s why the law and the prophets can be summarized as love God and love your neighbor.
We’re not permitted to “choose” our neighbor based on his money, personality, or position. We must love those out of our box, love the not-so-lovely, love those who need loving. Otherwise, failure in that one point makes us guilty of all.