A: Thank you for your question. Let me follow your lead by approaching it on the three levels of your question.
What does it mean?
Consenting to God’s presence and action within is the heart and soul of Centering prayer. Our consent might be compared to wedding ceremony where a “yes” is exchanged between partners. It is only the beginning. Then the wedding opens to a marriage which is lived out day by day. The couple are not only consenting to being together but to working through their combined “actions,” – the internal and external effects of being in relationship. Over time, each partner is changed by the relationship.
Centering Prayer is not only a relationship with God but also a discipline involving purification. Purification can be active and passive (see chapter 8 of my book, A Taste of Silence). In Centering Prayer, we take the initiative when we actively and faithfully enter into the prayer. As we consent in the prayer, then we let God take the initiative. We are saying, “Do with me whatever needs to be done so that I may be all that you want me to be.” In reflecting on my prayer time, I often imagine that Jesus was washing my feet; all I had to do is sit and receive (see John 13:4-14).
What does it look like?
As we consent to God’s action within, we are being healed of the obstacles to experiencing the Divine Indwelling – that God is always present with us. Deepening purification deflates our energy centers (control/esteem/security) and replaces them with true security, real affection and genuine control that have Christ as its center and source. “I no longer live, but Christ lives in me (Galatians 2:20).”
My good friend, David Frenette, adds this, "The radical consent of deepening contemplation means something even greater: saying yes to God's presence acting in you. As you continue in contemplation, you learn more about how to let God's presence act in you as the source of your prayer and the source of your life. … Your activity in Centering Prayer is like a rose's petals opening to the sunlight, like surrender unfolding inside you, like self-abandonment awakening within. Your action in contemplation is a radical consent to God's eternal nature more than your own self-initiated effort in one contracted moment in time. … In contemplation, you awaken to this indwelling reality, this gift of love that is the deepest center of your own being and the very heart of the world." (The Path of Centering Prayer: Deepening Your Experience of God)
How can I know it?
You will know it by the fruits of the prayer which begin to manifest in your life over time. In my life, inner peace has deepened, as has the ability to let go; the choices I make are different; how events come together is perceived differently; there is a greater capacity to embrace myself as I am and to enjoy just being (see Gal:5:22-24). And the capacity to take the words of Christ seriously has grown -- although there are many commandment and schools of thought, the two greatest are from Matthew 22: 36-40:
Love the Lord your God with all your heart, with all your soul and with all your mind.
This is the greatest and the most important commandment.
The second and most important commandment is like it:
Love your neighbor as you love yourself.
The whole Law of Moses and the teaching of the prophets
[and the teaching of Fr Thomas Keating] depend on these two commandments.
I hope these comments are a help; please let me know. I believe we could build a day of prayer pondering your three questions.
Blessings, Fr Carl
p.s. this verse from the hymn, "At the Name of Jesus," came along while I was pondering your question:
In your hearts enthroned him;
There, let him subdue
All that is not holy;
All that is not true;
May your voice entreat him
In temptation’s hour;
Let his will enfold you
In its light and power.
Is that not God’s action within in a nutshell?!