The sheep are provided with what they need (food from the Spirit) and they pretty much know right from wrong. They are sometimes herded with the staff (Authority/Spirit within) - i.e. they do sometimes make concious choices in regard to right and wrong and in their heart they are influenced by the Spirit - so it is with people all over the world in various religions. They chew on what is eatable before them, and move along to a bit more. Sometimes they can stray along way and get into a lot of danger/trouble, and the shepherd goes to get them.
The goats also have the food (Spiritual) they need, but aren't satisfied with what they have inside - then they take all the food that the sheep have. Then there doesn't seem to be any food - even for the sheep. The goats climb mountains, where they can find some higher food, and from where they look down - and the sheep move on to another field when the shepherd shows them.
The angels, i.e. the plain speaking humble ("we will sleep in the street"), the oppressed and handicapped, the innocent of mind, etc, sort out sheep from goats for the Lord, the Shepherd.
So who are the goats? Is it that hard to figure ?
Who chews away on the low ground, and who "eats upon the mountains"?
Bang