K.P.
It really depends on your relationship with the person. My godparents are my mother's sister and father's brother. Neither of them are overly religious, but my parents are strongly Catholic. While they had very little to do with my upbringing, both attended every important event in my life and walked eachother down the aisle at my wedding.
For my son, we selected my sister and her husband and they share the same level of religious practice. We are their twin daughters' godparents in turn. Having said that we are also the noted guardians should something happen and vice-versa. Much like my godparents, we will do our best to attend every important event in their lives and be there to support and encourage them just like ours did for us!
I always so my godparents as my second-best cheerleaders (right behind mom and dad)!