Matthew 12  Jesus demonstrates His authority as "Lord of the Sabbath" by first defending His disciples for eating grain plucked from the field, then by healing the man with the withered hand, and then by casting out the demon from the blind and dumb man.  In fact He healed all those that followed Him.   It is lawful to "do good on the Sabbath", He declares.  God desires compassion.  He values people.  Jesus proves that over and over again.

The Pharisees, on the other hand, hate this. They plan on destroying Jesus.  Their first step is to try to destroy His reputation by accusing Him of serving "Beelzebul".   How hideous is this accusation.  That Jesus Christ, the Son of God, the Messiah, the One who came to save, Who only did good... would be accused of belonging to satan... shows just how little the Pharisees knew God or satan. They could not even discern the difference between good and evil!

Three times Jesus calls these religious leaders "evil".
v34 "You brood of vipers, how can you, being evil, speak what is good?"
v39 "An evil and adulterous generation craves for a sign..."
v45 "That is the way it will also be with this evil generation."

Condemnation is coming for those not "with" Christ. (v30)  Jesus spells out their sinfulness.
v31 - They blasphemed the Holy Spirit.  They looked at a miraculous healing and deliverance of a man who could not see or speak, and proclaimed that satan did it.
v34-37  They spoke evil from evil hearts.   Whatever fills the heart comes out when we speak.  What we say either justifies us or condemns us.  Their words were evil, therefore their hearts were evil.
v38-42 They wanted a sign of their own choosing.  Signs were all around.  Everything Jesus did and said should have been enough.  But they wanted more.  They were worse than the people of Ninevah! That is pretty bad.
The words and actions of these scribes and Pharisees would bring judgement.  They brought it upon themselves.  Just like each of us do.  When we choose not to honor the Lord for the good that He does.  When we fill our hearts with evil instead of good.  When we ignore the Truth and seek after what we want God to do for us instead of being thankful and recognizing what He has already done.

Jesus teaches some other spiritual truths in this discussion with the Pharisees.
v25-29  A truth about kingdoms.   Divided kingdoms fall.  Satan won't cast himself out.  The only One who can cast him out is someone greater!  That is the Spirit of God.  Yes, Satan is strong, but God is stronger! Satan is bound up and can not stand against God!  Hallelujah!
v43-45 Unclean spirits seek rest.  They will come into unoccupied houses.  They take over .  The result is always evil.   If we do not have the Spirit of God occupying our hearts then we should not be surprised that evil spirits will take up residence there.

Father, how we thank You for saving us, for giving us hearts filled with Your Spirit!  Thank You for salvation through Jesus Christ our Lord.  We live in an evil generation also, that glorifies evil and refuses what is good.  A generation that fills their hearts with evil things and seeks their own desires.
Open our eyes to know You more!  To discern truth from lies.  Fill our hearts with Your Word that we may honor Your holy Name.  That we may do  Your will, for "whoever does the will of My Father who is in heaven, he is My brother and sister and mother." We are Yours Lord.  Your family.
Thank You!  Hallelujah, What a Savior!  Father, occupy our hearts.  Cleanse us from all evil that we have allowed there.  Let Your Spirit continually fill our hearts.  May Your fountain of living water never stop flowing in us.  That the strong man will never find even a foothold into our lives.  Amen!