The truth is that people who know no backsliding, have never existed except as figments of the imagination and of literary invention.
No Jew, even the greatest leader, saint, or prophet, has ever been free of religious problems, failings, heartaches, and doubts.
This is an established principle: everyone who takes the religious life seriously and who is thus ever striving onward experiences setbacks along the way.
It is not merely that "there is no one so righteous that he does only good and never sins," but more than this: temptation, doubt, pain, and transgression are the inevitable lot of those who would ascend higher.
To be sure, all seekers are not on the same level, and their failings are thus not equally grave.
A great person who falls back may still be on a much higher plane than others.
In both the material and the spiritual realms, "the righteous man may fall down seven times and yet arise."
Though he falls again and again, he continues to grope his way upward.
Indeed, this is the strength of the righteous: their ability to endure crisis, to bounce back, and to turn failure into a source of strength.
"The [thoroughly] wicked man," on the other hand, "falls once and for all"; once down, he cannot get up. His way is blocked, and there is no way for him to renew his ascent.
–Rabbi Adin Steinsaltz
From "Lapses and Crises" in Teshuva by Rabbi Adin Steinsaltz