It depends on what you need. The first thing you need is that the counsellor be competent. No one would go to a physician who, though he was Christian, had failed to pass medical school, yet a significant number of individuals present themselves as Christian counsellors and fail to meet the minimal standards of education, licensing and accountability to a professional organization described above. Whether your counsellor should be a believer also depends on the issues you will be addressing. Not every counsellor who is a believer has this training.
Some counsellors are uncomfortable working with a pastor as part of a helping team.
While there are times it is appropriate not to include your pastor in the counselling process, to completely rule this out may prevent you from receiving the fullest range of help possible. Many believers prefer to see a counsellor who is a believer because they are afraid that a non-believing counsellor will interpret their faith in Jesus as harmful and attempt to convince them to reject Jesus. It must be clearly stated that professionally it is considered unethical for a counsellor to attempt to change the faith of a client. A counsellor works for the client and as such has been hired to help the client deal with particular problems. While it is appropriate to talk about your faith during counselling, it is inappropriate for a counsellor to exert pressure on you to change your faith.