After Jesus told the parable of the weeds (Matthew 13:24-30), His disciples came privately to ask Him what the parable meant (Matthew 13:36).  Many people in the West have got used to depersonalising the spiritual influences on our lives.  They prefer to think about 'forces of good and evil'.  Life is then a matter of human skill in manipulating those 'force fields'.  But such ideas are wrong, completely wrong.  The Bible talks about a personal God, and the person who opposes God is the devil.  In the parable, the sower is Jesus and the weeds are Satan’s workers.
 
The devil is not just evil, he is the Evil One.  He is the tempter who distorts truth into lies, persuading people to believe the lies and reject the truth (John 8:44).  His temptations are not constant and predictable, nor do they come to all humanity randomly.  The Evil One knows our personality, our track record of obedience and disobedience to God, our moral weaknesses and our deep desires.  So the devil will tempt us specifically: testing our weak areas and trying to draw us away from a whole-hearted devotion to Jesus.  Satan is not alone: he is helped by people who have been poisoned by his deceit, and they reinforce his lies.
 
The Son of God is not a 'force' or 'influence' but a person: we know Him as the Lord Jesus Christ.  The apostles knew that His character was more than good; He demonstrated that He is God (John 1:34; John 20:31).  He is the Truth (John 14:6) and everything He says is a seed of truth.  When received in a person's life, it transforms people from being the 'people of the Evil One' to being 'the people of God's kingdom' (Colossians 1:13).  This transition is all under God's power.  The Evil One does not have the right to control this world indefinitely because God's angels will deal with people who do evil, so that they cannot pollute His kingdom.
 
Some think that God and the devil are equal and opposite forces.  But they are not forces, they are personalities; but they are not equal, for God is infinitely superior.  The apostles had to understand this.  Their gospel work would have the power to pull down Satan's strongholds (2 Corinthians 10:4).  Their battles would not be with people but with the Evil One (Ephesians 6:10-18); nevertheless, they just had to stand their ground and see how the Lord would win (2 Chronicles 20:15).  So do not be intimidated by the Evil One, or think that you can manipulate him: simply trust the Lord and accept His protection as He deals with the opposition.