The soul must be distinct from intellect because even at its best, what the soul does when it's thinking, is it thinks linguistically, it thinks in a temporarily extended way, so it for example, might go through the steps of an argument chain, as if you were going through a syllogism and seeing that something followed from the premises, whereas intellect simply grasps the forms.

Unlike later Neo-Platonists, Plotinus says that our souls are always connected to the universal intellect and that we never really fall away.

I'm sure that Plotinus wasn't that impressed by the Christians.

If you think about even very common examples like, say, something that you would build, like a clock or a car or a group of people trying to accomplish something, it fails when its unity breaks down. So when it stops having a single form, which is functioning all together, then it sort of falls apart into discrete elements.

Soul puts the determination or forms or images of forms, into matter.

People often talk about Plotinus' system. The reason they do this is that Plotinus postulated a kind of series or chain of principles, so at the top there's what he called the One. Below the One is what he called Intellect. Below Intellect is Soul, and the effect of the soul is the physical world that we actually live in.

Plotinus is usually called the Founder of Neo Platonism and what that means is that in this philosophical circle, he was founding a kind of renewed attempt to understand the thought of Plato which however they were combining with the thought of other philosophers, including Aristotle, the Stoics and Pythagoreans and so on.