How far removed is saying "So-and-so doesn't pray" from saying "So-and-so is a disbeliever"?

A Muslim must be extremely cautious about what he says, for he is accountable for every word. It is not permissible to delve into people's honor without clear evidence, because a Muslim's blood, wealth, and honor are sacred. Whoever accuses a Muslim of a sin without evidence has committed a grave transgression, as Allah Almighty says: "And those who harm believing men and believing women for [something] other than what they have earned have certainly borne slander and manifest sin." Accusing a Muslim of not praying is not equivalent to accusing him of disbelief, because scholars have differed regarding the ruling on one who abandons prayer out of laziness, and the majority of them do not consider him to be an apostate whose disbelief removes him from the fold of Islam.