Well most churches are certainly going to be lacking in their sex education as well. I would not be comfortable with my child only getting a church's view of sex.
And that is ok. Each parent raises their children differently based on their values and opinions. If my church had an inadequate program, I may feel different. However, with things as they are as such... whereas my sons may receive a program from school, their primary sex education will come from myself(and wife of course) and from my church.
Fortunately, they are way to young for me to have to worry about it right now. However, I know that the time will go by too quick.