Because I Received Authority by Grace, How Could My Personal Conduct Affect My Ability to Minister Healing to Others?

First, if you’re an obnoxious moron, no one will want to listen to you, and that would definitely restrict your ability to minister healing.

Second, Jesus taught that your lifestyle CAN affect your ability to minister.  The disciples failed to cast out a demon even though they already DID have the authority to cast that demon out.  They let unbelief override their faith because they had not been praying and fasting (Mark 9:17-29).

Third, Paul taught that you’re “fit” for the master’s use if you’ll put aside fleshly things.

2 Timothy 2:20-21:
But in a great house there are not only vessels of gold and of silver, but also of wood and of earth; and some to honour, and some to dishonour.
If a man therefore purge himself from these, he shall be a vessel unto honour, sanctified, and meet for the master's use, and prepared unto every good work.

A more consecrated person will have an easier time doing the works of Jesus than a person who tries to see how much sin he can get away with.

Fourth, certain sins completely disqualify you from functioning in a ministry office.  If your kids act like demons and terrorize the local elementary school, or if you’re a lover of money or a drunk, you are no longer fit to be an elder or a deacon, let alone any other kind of leader in the Body of Christ.  While you would still have the legal right to minister healing because of your authority in Christ, having to be removed from a ministry position will certainly interfere with your ability to have others take you seriously and receive from you.

For more on this topic, refer to Healing and Consecration.