The wording is a bit odd. I should think unlikely beyond belief that the vicar's feelings would be "hurt" by a teenager stopping coming to church. Firstly, because it's all too usual for teenagers to stop going to church, and secondly because although the vicar might be concerned about one of his flock losing their faith, he's not going to be personally hurt - unless he's a particularly self-obsessed character who relates everything to himself. The Marlows have only been living in the parish for a year, so it's not as if he's known her from small childhood having baptised her etc. It does seem like a case of the unconscious arrogance that the Marlows are often accused of.
If Mrs Marlow is embarrassed the solution seems obvious. Take Lawrie to church every week, and every other week tell the vicar it's Nicola.