The question is very simple, "does intention matter"? The answer is also as simple in one word, yes.
Power and importance of intention is accepted by religious and spiritual minds all over. Everything that we do or say has an intention behind it but mostly, thoughts and intention are interwoven. Power of both has been discussed much almost everywhere and has been accepted as reality but many are still skeptical about power of intention because there are fine lines between the two and it is sometimes hard to differentiate. There might be other reasons but probably one of the causes is that human mind is not yet able to explain the working and even existence of all the energies in the universe. Thought is one form of energy that has been only partly understood and explained; and its relation with intention is even more complex.
Thoughts affect our physical beings tremendously. Have you ever noticed that thought generated by sudden news very powerfully affects the functions of physical body? There are countless incidents where sudden bad or good news caused instant rise or drop in blood pressure or even caused heart failure. Such is the power of thought. In a milder form; stress, which is also a form of certain thought pattern can produce mild effects like diarrhea, insomnia or loss of appetite etc.
Similarly, the intention also has its effects. Something done with genuinely good intention usually brings positive results while ill intention does the opposite. This concept might not be very appealing to some because it is a non-physical factor; however, it has its own effects on our lives. Let us take few examples. If you stand up for prayers in your worship place but actually do not intend praying; you stand there just to show off. Do you think it will be accepted as prayer? Certainly not, because God knows your true intention. Similar is the case of Reiki treatment. If the healer places the hands but does not actually intend to heal, Reiki energy will not flow and the healing will not take place. And so on — there can be numerous examples where true intention produces different results as compared to true intention.
The effects of intention are not restricted to any particular field; they can be experienced in every field and can be observed in various matters. The intention may be good or bad; the results appear according to our true intention working through subconscious mind whether or not we know that consciously. The intention matters and undoubtedly has an exceptional power. Needless to say that true intention cannot be concealed from Nature; it is not possible.