Manifestation is a simple process. So many make it more complicated than it really is, which only serves to negate the whole process. Too many make the mistake of thinking that they can control Spirit, or control the manifestation. It's revealed in their language. When one says, "I'm allowing Spirit to take control," they're really not. If, however, one says, "I'm receiving such great things from Spirit right now," then they are apparently giving up control of the manifestation. That, most likely, will cause those things to come to be more quickly.
So what is the difference?
"Allowing" means that we control when and how something comes. Sometimes, though, we really don't. In that case, when we apply this particular distinction to what we want out of life, we come to the conclusion that we must receive, rather than allow.
"Receiving" then means that we do not control when and how our desire manifests. Instead, it means that we are letting Spirit take control of the who, when, where, and how, although we already know the what and the why.
For example, if a friend decides he's going to give me a twenty dollar bill just for the heck of it, would I be allowing or receiving? If I were to allow it, it would mean that I was trying to control every aspect of it. The who would be fine with me. The what would have already been decided by my friend. But the when where why and how must be in my control, must be my decision.
But if I simply "receive" from this friend, rather than "allow," I would not be in control of any of the situation. The who decided the what and the when, as well as the where and the how, and finally the why. The friend would've made the decisions that covered all of that already. My job would then be simply to give him thanks for it, and put the twenty dollar bill in my pocket.
So rather than "allowing" Spirit to do something great in our lives - being in control of certain aspects of the manifestation - why not just "receive" of Spirit the thing we desire. Why take control of it? I believe we should simply let Spirit decide all the aspects and joyfully receive. It's much easier that way. Let Spirit decide what comes, who it comes through, when it will manifest, where it will start the manifestation process, why it is manifesting, and how it will manifest. Simply receive what it is you desire, rather than allow it.
By the way, the term "allow" also implies that you control Spirit, when in fact, Spirit controls Spirit. So it's easy to try to take control and command Spirit, when we're not about to do that. It's not that we're lesser forms or that it's not acceptable to Spirit. It's simply that it's easier for us if we give up control, and then "receive" rather than "allow."