It is one thing to believe in Jesus Christ. It is another to believe in the Holy Spirit as a reality for today. Two kinds of signs exist to help us believe. There is one kind of sign which comes with one kind of working of the Holy Spirit. It is a kind of sign which can accompany a gift of prophecy. Here the prophecy itself announces a sign. The sign might then be something visible to all who hear the prophecy, perhaps as something new or very unusual. Another kind of sign is the gift of tongues. Here it us the form of the message which is itself the sign, where the message is given by the working of the Holy Spirit in a language not known to the speaker. It might be human and foreign, or it might be angelic and supernatural. The sign is further given when the interpretation is given, either to the speaker or to a hearer or both. If given to both speaker and hearer it can reinforce the sign to help those who hear the message to believe. These gifts might be given in a setting of a gathering of believers for worship. The actual working of the gift in the case of prophecy might precede the service meeting and then be spoken out in the meeting. Confirmation might come in the meeting by several gifted people having been given messages which are first found to corroborate each other when spoken together in the meeting. All these help to reinforce the message as coming from above but to be sure they are workings of the Holy Spirit they still need to be tested by using discernment regarding their content, and by the kind of character they build. If the tree is corrupt, the fruit will be corrupt. The Holy Spirit gives pure gifts and produces pure fruit.