Believers should be open to and encourage the Spirit's moving within each one, including the spontaneity from individual initiatives when gathered together. Believers need to be vigilant to prevent formality of liturgy where the Spirit is stifled, and individual initiatives are not allowed.
When a person denies his conscience for too long, it can become seared. That person becomes susceptible to receiving and accepting all sorts of harmful and evil things. This is true for both believers and unbelievers. A seared conscience will open a person up to demonic spirits and activities.