It may be true that the parable of the sower is the fundamental parable of the Kingdom of God.
Then he told them many things in parables, saying: “A farmer went out to sow his seed. (Matthew 13:3)
The first thing we must remember is that the Seed is Christ. The Seed is the Resurrection and the Life, and all righteousness, holiness, love, joy, and peace. The Seed is the Kingdom of God.
When the Seed fell on hard ground it did not germinate. It lay there exposed. Satan came and removed it. This is like a person who has hardened his or her heart against God. He has permitted many different religions and ideologies to trample on his heart.