It's definitely a case of developing a strong sense of values. The children are, of course, taught about the story of Christ, but they are also taught the basics of several other religions. The school has a very strong relationship with Llandaff Cathedral, so the pupils attend one service every week Y3 upwards. The school choirs (both girls and boys) sing for the Cathedral's services, and it is a joy to listen to them. But overall, it is about fostering an ethos of tolerance, hard work, and compassion. Very old-school, but with new-school kindness 
In Infants, they have traditional nativities at Christmas with a baby Jesus etc (which I really like, personally) but it becomes less religious the higher they go up the school.
I should mention that the current school priest is a gem, and his main focus is to provide pastoral care to all the students, irrespective of which faith they come from. I attended his Christingle service last year and he made it very accessible (I am not from the Christian faith)
It depends on where your line of comfort is though. I have personally never found the school overbearing on the religion front! To be honest, I am fairly confident Howells is the same in this respect. I have never heard any parent grumble about this over the years.