1 John 2:19 They went out from us, but they were not of us; for if they had been of us,
they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us.
You answered your very own question in your very own next post.
1 John 2:19 They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us.
SD