The idea of the Light is one of the basic concepts taught by MSIA. The Light is a powerful force and is a manifestation of God on this physical level. Sometimes this spiritual Light is called the Light of the Holy Spirit. The Light is what God uses to get something done here on Earth. It is inside each of us and is what gives us life.
The Light cannot be seen with our physical eyes, although it can be seen or sensed spiritually. Just because it cannot be seen physically doesn't mean that it doesn't exist. There are many ways of demonstrating its existence to yourself. Some of these are suggested in MSIA's book, Manual on Using the Light. MSIA doesn't teach blindly believing in things; instead, we suggest that people check things out for themselves, and there are techniques explained in the book for checking out the Light, its existence, and how to work with it for the highest good of all concerned.
To give a little more detail on this, there are two aspects of the energy of the Light: one is called the 'magnetic light,' and it is an energy of the lower realms (below the Soul realm). You, consciously or unconsciously, are an individual director of it. The other aspect is the spiritual Light, which comes from the positive realms of pure Spirit (the Soul realm and above). The Light of the Holy Spirit can and does come into the levels below the Soul level by riding on the magnetic light as a vehicle. You cannot get the Holy Spirit without the magnetic light because the Holy Spirit comes in on it. However, you can get the magnetic light without the Holy Spirit.
When calling in the Light, we always ask 'for the highest good of all concerned.' We do this in order to invoke or work with the Light of the Holy Spirit, which will never inflict itself on anything or anyone. It comes only where invited, and it operates for the highest good of all concerned. When you are doing anything different from that--for example, trying to control the outcome of a situation--you are dealing with the magnetic Light, and there are always strings attached, and later on you may have to balance an action in which you tried to control or manipulate events or people without taking 'the highest good' into account. When you stay out of trying to control and ask always for the highest good, you are more likely to be dealing with the Light of the Holy Spirit.
For more information about the Light, see the Frequently Asked Questions (FAQ) section about the Light and the MSIA Prayer List or check out the suggested resources for further information.