Painful Thoughts

I was told something recently that hurt more than I expected it to.  A person who is family but that I have never been close to told me that he sees what I am doing as useless.  We (I'll call him Dave as a reference even though this isn't his name) were talking about my schooling and he absolutely shocked me.  Just as I am finishing my master's in philosophy (after an M.A. in theology) he told me that I wasted my time studying.  At first my attitude was like 'whatever, you can think what you want and be wrong.'  But upon further reflection, I'm having a really hard time with his comments.  I have worked very hard in my program and do see them as extremely valuable, perhaps the best experience I have had so far in my life.  So to be told that Dave thinks I am wasting my time cuts like a knife.  I went on to ask him what he thought would be useful to do in life and he gave some generic answer like 'help others and serve God.'  This answer continued to sting because it indicates how little he understands what I am doing.  My whole purpose (at least at this point... maybe not on the beginning) of studying philosophy and theology is so that I can understand (and then love and serve) God better and then be able to pass this knowledge onto others.  Granted it is not feeding the homeless or smuggling Bibles into wherever, but I want to be part of the battle for minds and hearts against the Devil's stronghold of naturalism.  I want to help people understand the importance of thoughts and beliefs and their great impact on actions.  While I may have experienced a small taste of the ivory tower, I really want to hit the ground running and truly make an impact.  Perhaps this is the heart of the problem; if I cannot get Dave to understand what I am doing, is there any way that I will be effective to a broader audience?  Is this an indication that I am doomed to fail?  Or should this exactly be the motivation to help others understand how important ideas are?  How do I move from hurt and frustration to compassion and determination?  

Lord God, please help me understand the path that you have for me and give me the courage to live a flourishing life that serves the kingdom.  I am so grateful that I do not have to walk this path alone but that you are with me every step of the way and know what the future holds.  I am grateful that God uses small instruments like me for his glory in ways that he knows is best.  I'm having a hard time, but I'm still trusting.