Jesus listened to the words spoken by others but His answers were for or against the spirit. When Peter announced that He was the Son of God Jesus responded in the affirmative. The same Peter a few minutes later said Jesus would not die on the Cross and Jesus rebuked Him for saying it and blamed Satan for it.How does the same person manifest God's word and Satan's word? This is possible when we know that both God and Satan are at work. This is why our tongue is a powerful agent to bless or to curse. We determine who will use us. This maybe an admonition to us to watch what we say. We have the authority on earth to curse or to bless.
Example
I remember at one prayer meeting in Dundee that I cursed the night club beside the church. Six months later it got burned down but the church was spared. I still am amazed that it happened! When we walk in the Spirit, evil will come against us but we have the authority over every serpent and scorpion to crush it under our feet. In these days of turmoil we need to bless what is good and curse the things that God hates. This may sound drastic but the Kingdom of God suffers violence and we have to take it by force by praying in the Spirit.
Discernment
Identifying the spirit behind the words is easy when we choose to walk in the Spirit. Our responses will be in the Spirit. This is how Jesus confused the religious in His day. They just were paralysed in their responses as He bound the spirit that was talking through them. All they could do was to scheme to kill Him. The devil always is in the business of stealing, killing and destruction.Therefore we know that gossip and slander is of the devil. Anything God hates we must hate, like killing babies and euthanasia. This is not an opinion but standing on God's revealed will. We must stand for justice and righteousness and be the salt and light where He has planted us.