The parable of the mustard seed continues with the same central thoughts set forth in the previous parable, the parable of the wheat and tares. Fruit-bearing remains at the forefront [v.31], as well as Satan's contining activity as he seeks to stop Christains from bearing fruit
And the method which Satan uses as he seeks to stop Christians from bearing fruit, revealed in the previous parable, is through sowing tares among the wheat. Then the parable of the mustard seed reveals that which would happen because of this activity of Satan.
In this respect, the parable of the mustard seed is simply a commentary on the previous parable, providing additional explanatory help. The mustard seed is seen growing after an adnormal fashion, showing Satans success in stopping Christains from bearing through causing an unnatural devoloping so abdormally that it eventually became a tree; and this tree is seen to be of such a nature that" the birds of the air", indivduals doing the work of Saten, found a lodging place in its branches[v.32;cf.vv.4, 19.] Thus the third parable, continuing the thought from the second parable, presents the tares being quite effective. They are seen deciving Christians to the degree that they bring about an unnatural growth in Christendom, resulting in unfruitfulness, barrenness; and the matter is carried to the point that, in the end, the tares even found acceptance among those whom they had decieved. Through producing an unnatural growth in Christendom-- one in which they themselves could find acceptance-- the tares stopped Christians from bearing fruit. The destruction has to do solely with [ The Word Of The Kingdom], the subject matter at hand. Then the tares were able to simply settle down in that which they had produced.