This means Listen to My Voice, Learn to undo the error, and do something to correct it.
The first two are not enough. The real members of my party are active workers. (Urtext version of T-1.III.1:5-6)"
Are you willing to be an active worker in Jesus's plan of atonement, working miracles for others and lifting your brother into awakening? Or are you only interested in undoing the error for yourself?
This is perhaps a major distinction in the course community. Those who listen to the Voice for God and undo error, versus those who did this but also then 'take it to the people' with expressions of love and miracles. Jesus says he wants us to be miracle workers for others and not just for ourselves.
"Having been restored to your original state, you naturally become part of the Atonement yourself. You now share my inability to tolerate the lack of love in yourself and in everyone else, and MUST JOIN THE GREAT CRUSADE TO CORRECT IT."
Does this not mean, that you must now actively help others to awaken? That you would naturally want to do this because you love your brother so much? That you would ACT upon this love and express and extend it to others, even intervening for them with miracles (miracles intervene for their holiness). If you truly are in a place of love, then you will become part of the atoning principle, the atoning 'plan' for salvation, of which Jesus is in charge, and then you will be a part of helping to awaken your brother. It's not a crusade like a conquest or war to 'attack' the ego, but rather to heal and help others to be restored to their natural condition (divine health, perfect mind) and to demonstrate and be an example of the truth, sharing it with everyone. It is a calling, to be a representative of God here, while the illusion persists.