When you have raised the dead to life at your words,when you have healed the sick and lame by laying a hand on them, when you have calmed the angry sea, when you have spoken to demons in a persons body and the demons leave, when you have taken some fish and bread and fed over 5000 people. When you have experienced the power of God in your life, and then you turn around in your convictions and decide to follow satan, then you will have committed the unpardonable sin, turning from Jesus and turning to satan.