“Again, the kingdom of heaven is like a net that was thrown into the sea and gathered fish of every kind. When it was full, men drew it ashore and sat down and sorted the good into containers but threw away the bad. So it will be at the end of the age. The angels will come out and separate the evil from the righteous and throw them into the fiery furnace. (Matthew 13:47-50)
In these parables, Jesus is teaching about the Kingdom of God. The Kingdom of God is like a fishnet, or a pearl, or a treasure. There are at least two different aspects of the Kingdom that Jesus is trying to convey in these short parables. First, the kingdom is like a man who buys a fine pearl or a field with a treasure in it. These items both represent us, human beings, those whom God calls. We are a very precious item which He, Jesus, buys or redeems with the cost of His own humiliation and death at the hands of sinful men. Secondly, the kingdom is like that man who buys the field to get the treasure. Most of the field is without treasure, but he has to buy the whole thing in order to get the good part. It is also like the dragnet which takes in many edible fish as well as some items that are unclean. The whole may look massive but the sorting done after the net is brought in to shore will tend to reduce that.
The parable about the dragnet as well as the other preceding parables, appears to speak about the outward nature of the Kingdom of God. That Kingdom, the one we can see on earth, seems to be huge but its size is highly inflated. Not everyone who is connected to it belongs in it. Like the man in one of the preceding parables there are weeds mixed in with the good wheat. So it is with the church. There are many who profess to be Christians, currently over 2 billion by most assessments, making Christianity the largest world religion in terms of numbers. Many of these are true believers. But many are also liars, false prophets, heretics or simply deceived. The Lord when He returns at the end of time will sort things out. He knows those who are His and will preserve them unto eternal life.