A belief in separation takes place within your own mind. Your own mind becomes divided. A portion of your will goes into one part and the rest into another. Eventually this forms the conscious self and the unconscious self.
Separation leads to a splitting out of cause from effect, receiving from giving, and other from self. But because it splits the will, it results in two opposing wills which do not see things the same way.
"Being in two minds" means having an ego mind - a divided mind at war with itself. It must produce indecision and an inability to resolve conflict. It in fact must produce conflict, because one part of will is acting to cancel out the other. This creates a standoff, or a stalemate, or a situation of simultaneous push and pull.
The result of two wills acting against one another in opposite directions is that they will cancel the effects of each other and create a paralysis. One will tries to move in a given direction, the other will stops it. The other will tries to move in a given direction, the first will stops it. Nothing happens.
With two opposing wills trying to operate at the same time, there must conflict - an inner war with yourself. You will thwart everything you try to express. This conflict is literally the same thing as insanity, because the single whole mind is attempting to achieve two opposite and incompatible goals at the same time. It produces impossibility - which is the opposite of the possible. Miracles are another name for possibility. And with God, all things are possible.
When you are in this world and are in two minds, ie you have an ego and therefore two wills, you are literally against yourself. You are experiencing self attack. Your will and ambitions will be thwarted, sabotaged and undermined. You will become "stuck", ineffective, powerless and frozen.
Ultimately this leads to fear which will stop you in your tracks. Fear is a state of intensely experiencing separation between yourself and yourself, where one part of you seems like you and the rest seems like a separate enemy. Fear is paralyzing. It puts a freeze on action, it strips both parts of mind of all power, collapses the power of will and is an attempt to extinguish yourself.
No wonder then that when your mind is split, you cannot manifest miracles, you cannot see yourself as sharing God's power, you do not see yourself as causal, and every time you try to even perform a miracle it becomes thwarted and nothing seems to happen. You get used to this mode of being un-mraculous, believing it is normal to have no power over anything.
The only reason you can't make objects move, raise the dead, heal the sick, levitate or whatever else, is because your mind and heart is not WHOLE, with a single focus or goal. It is divided against itself. You try to cause stuff to happen, but the rest of you tries to stop it.
A simple example is that you attempt to produce a miracle but you "ask" for something to change, you fear that it won't change, you have doubt about seeing results, you look to form to change to see if something worked, and generally undermine yourself. You waver. You lose sight of the truth. You listen to other people's doubts and buy into the appearance that it isn't working. You listen to the ego. And this basically cancels your efforts.
But you'll think that all of these things are happening against your will or that you're really trying hard to make this miracle happen. PART of you is. ONE of your wills is. But you have another separated will - part 2 - which you are still actually USING, albeit largely unconsciously, to sabotage your efforts.
Your belief in fear splits your will. Your belief in a lack of authority splits your will. Your belief in not being completely causal, or not having power over anything, splits your mind. If your mind becomes split like this, you are literally working against yourself. One hand is reaching to express a miracle, the other quickly wrestles with it and stops it. Not physically, but in your mind and perception.
To work miracles requires an allegiance to the truth, and a loyalty and clarity about staying true to it no matter what illusions present. Holding fast regardless of things appearing to not work, or even if they seem to become worse. Is it the truth? No. But if you take it in and make it real, that's you using the other half of your will against yourself.
The only reason that a miracle won't happen, effectively, is because you stopped being causal and turned yourself into an effect. You paralyzed yourself - dis-empowered yourself. It is your false perceptions which strip you of your sharing of God's power. You can't work miracles when you're divided against yourself and thus God. It's like asking God to stop flowing. It means you do not really know what you want, and uncertainty does not produce the certainty of God's power.
Another way of saying that is that when your mind/will is split, you are asking for two things at once, which is like asking for nothing clearly at all. So you get nothing, or you "mis-create", and end up with effects that you don't think you asked for.
When you "ask" by focusing on only one thing, wholly and clearly, it must be given you. Therefore realize if the only thing stopping your miracles was your own divided will, once your will, mind and heart are whole, you will not stop yourself, and no-one else has any power to do so either. Anything is possible.
Being so used to having a split will, which renders us practically powerless and inept, we are not accustomed to being solely causal. We are not used to the power of the mind when it is expresses in one direction, with one intention, one focus, one belief, one thought, one love. We are not accustomed to giving and receiving being one. And we are not used to having so much authority over illusions.
The mind has massive creative power. It never stops being creative, Jesus says. It's just that we keep using it against itself and thus keep mis-creating, producing effects which conflict with part of what we asked for, or we create things which attack ourselves, or things which seem unwanted or a mistake. There are no mistakes. You ARE getting what you're asking for, it's just that you keep asking from a confused state of not really knowing what you want.
What happens when you cause and you do not stop yourself? You create. That's what produces miracles, manifestations, signs, healings, wonders, etc. Jesus was masterful at this, coming from such a state of pure love that He could express all of God's power, undivided, certain, with great authority, and there was nothing He could not do. You can be this way also.
I asked Holy Spirit how better to produce miracles. He said, "be truth." Truth is absolute. All or nothing. Commitment. Certainty. Confidence. Authority. Power.