For you did not receive a spirit that makes you a slave again to fear, but you received the Spirit of sonship. And by him we cry, “Abba, Father.” Romans 8:15
Being led by the Spirit does not enslave us; rather, God's spirit gives us the realization that we have become adopted sons of God. For that reason, we cry out “Abba, Father.” In adoption all previous relationships are severed. The new father exercises authority over the new son, and the new son enters into the privileges and responsibilities of the natural son. “Abba,” the Aramaic word for “father,” was used primarily within the family circle; it underscores the intimate nature of our relationship with God, which is so clearly the opposite of fear.