I found a very interesting text in Hebrews 6 in which Apostle Paul also spoke about thorns (akantha/G 173):

Therefore let us leave the elementary teachings about Christ and go on to maturity, not laying again the foundation of repentance from acts that lead to death, and of faith in God,

instruction about baptisms, the laying on of hands, the resurrection of the dead, and eternal judgment

And God permitting, we will do so.

It is impossible for those who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit,

who have tasted the goodness of the word of God and the powers of the coming age,

if they fall away, to be brought back to repentance, because to their loss they are crucifying the Son of God all over again and subjecting him to public disgrace.

Land that drinks in the rain often falling on it and that produces a crop useful to those for whom it is farmed receives the blessing of God.

But land that produces thorns and thistles is worthless and is in danger of being cursed. In the end it will be burned (Heb 6: 1-8).

Apostle Paul dealt with several issues in these verses:

  1. the need for the Hebrew believers to move from elementary school to a higher dimension of learning in things pertaining to Christ. The King James version renders Hebrews 1: 1 as follows: –  Therefore leaving the principles of the doctrine of Christ, let us go on unto perfection (teleiotēs); not laying again the foundation of repentance from dead works, and of faith toward God. Teleiotēs is translated  as the state of the more intelligent and  moral and spiritual perfection. It is found only in one other text and that is Colossians 3: 14.
  2. The Apostle also spoke about the falling away of believers who were once tasted the Word of God. Based on the Greek word, to fall away means to deviate  from the right path, to fall away (from the true faith): from worship of Jehovah (http://www.blueletterbible.org/lang/lexicon/lexicon.cfm?Strongs=G3895&t=KJV)
  3. Just as Jesus did, Apostle Paul compared the spirit of the believer to the earth or soil. Soil drinks in the rain or word of God in order to produce useful, good fruit.  
  4. While the Lord Jesus said in the parable that the believer with thorns do not bring fruit to perfection, apostle Paul added in his letter that these individuals will be burnt. In fact,  although the Lord left the outcome hanging in this parable, we know from His other teachings that the eternal future of these individuals is not a pleasant one.  Jesus said that they will not enter heaven (Mt 7: 15-23); they will be burned with fire (Jn 15: 6).

My encouragement is to remain in Christ.  When I return in the will of the Lord, I will write about the thorns that the Lord Jesus spoke about in His parable. Blessings!