What is the ruling on accusing someone of apostasy from Islam because he associates with an unveiled woman?

It is not permissible to be lenient in labeling a monotheistic Muslim as a disbeliever, for it is one of the major sins. The Prophet, peace and blessings be upon him, said: "Any man who says to his brother, 'O disbeliever,' one of them has surely fallen into disbelief. If it is as he said, then it is so; otherwise, it returns to him." It is incumbent upon whoever wishes to denounce an evil or admonish a disobedient person to do so with gentleness and kindness, for Allah is Kind and loves kindness. Uttering such words may repel the person and make him persist in disobedience. Going out with an unveiled girl is not considered disbelief, but rather a sin because it is a means to falling into indecency. The doer should be advised gently.