Faith is defined as, “believing and acting on God’s word as quickened and applied by the Holy Spirit”, while the dictionary defines “presume” as, “….to perform, do (something) without authority; to lay claim to without permission”.
    Though faith and presumption may look or sound alike, they are vastly different. The similarity between them is the reason why well-meaning Christians sometimes mistake one for the other. This can have some negative consequences, as can be seen in the experience of the seven sons Sceva, who were severely beaten up and humiliated in a failed attempt to cast a demon from its victim (Acts 19vs11-16).
    However, when faith and presumption are juxtaposed and closely examined, a sharp fundamental  contrast is observed. This basic difference between the two is what accounts for the distinction in their outcomes.  Let us now use the account of the sons of Sceva as a case in point for the analysis of the difference between faith and presumption.
    Prior to telling the experience of the seven sons of Sceva with the man who had an evil spirit, the bible records what God had done by the  hand of Paul: “Now God worked unusual miracles by the hands of Paul, so that even handkerchiefs or aprons were brought from his body to the sick, and the diseases left them and the evil spirits went out of them”. (Acts 19:11,12).
    The unusual miracles God had worked by the hands of Paul, must have aroused the fascination of the sons of Sceva so much that they wanted to be able to perform such miracles too. That led to their unsuccessful attempt at imitating Paul. Many contemporary equivalents exist. It is common today to find people, who demonstrate by their actions (and utterances, sometimes ) that, an unusual display of the power of God observed in a person’s life, can be re-enacted simply  by copying the person’s outward actions. Nothing could be further from the truth. That was the mistake the seven sons of Sceva made.
    They did not realise that underlying Paul’s success, was the principle of faith in action, and not presumption. That the conclusion just made is correct is proven by the following expression, “THEN some of the itinerant Jewish exorcists TOOK IT UPON THEMSELVES to call the name of the Lord Jesus over those who had evil spirits” (emphasis mine) (vs 13 ). Taking it upon themselves, implies that they arrogated authority to themselves, and that was a usurpation of God’s prerogative. Only on God’s terms is the right to the effective use of the name of Jesus given. The word “then” in the quotation above is informative. It reveals and buttresses the earlier assertion that, the  sons of Sceva, like the said Jewish exorcists of their day, had been observant of Paul and his approach to deliverance. My explanation becomes clearer, if you substitute the word “therefore” for the word “then” in Acts 19 :13, because it shows the relationship between what God had used Paul to do in verses 11,12 and what the sons of Sceva had done in verses 13 to 15.
    Further more, we are told that they attempted exorcing the evil spirit by, “the Jesus whom Paul preaches”. It is evident, therefore, that they simply imitated what they had seen or heard Paul do. However, their efforts were not only unproductive but also counterproductive, as they fled the house bleeding.
    The most important lesson to learn here is that authentic faith is initiated by God Himself. It is not of human origin. That is why the Bible says in Romans:10.17 “So then faith [comes] by hearing, and hearing by the word of God.” This is the reason why you should not simply imitate someone’s actions of faith without having experienced the revelation knowledge that underlies it. For instance, you should not sell your house and give away the proceeds because you either saw, heard or read of someone who had done that and was  rewarded. Taking a similar action will not guarantee similar results. It takes having similar revelation knowledge to experience similar outcomes. Shalom.