Last Sunday, I went to church! I more often spend my Sunday mornings gardening, but this was a family christening in a small seaside town in south Devon. I have known this church all my life, but it – and the morning service – had been transformed. The pews had gone, great glass walls were in place and the whole place seemed larger and brighter. The deeply religious atmosphere I remembered (though possibly falsely) was gone, too.

More different still was the service. I knew none of the jolly "songs", nor the cheerful responses, and I drifted off into reflections on the familiar stained glass, until the words I was hearing brought me up short.

What was this? I checked in the nicely printed service booklet. Yes, the baptism part began with a reading from Mark 10 13-16: "Whoever does not receive the kingdom of God as a little child will never enter it." Not that I want to enter it, and come to think of it I did receive it as a little child, but are Christians actually supposed to believe that if you are not baptised young then that's it? Or is this one of those things they quietly admit they don't really believe even though they are happy to hear their vicar read it out as though they should?

The godparents and family were asked to pray for the little boy, draw him into faith, and not be ashamed to confess the faith of Christ. The pope's visit being still in my mind, I thought of his encouragement to Catholics to make the sign of the cross and say "God bless you" to people. Then the warfare started. "Fight valiantly as a disciple of Christ," the baby was told, fight "against sin, the world and the devil."

OK. I know there's lots of "Onward Christian soldiers" stuff in this religion. Don't take it too seriously, I thought, as I listened to the vicar urging this little new soul to "be prepared" and reading from St Paul's letter to the Ephesians: "Put on the whole armour of God … wiles of the devil … struggle … forces of evil … stand firm … put on the breastplate of righteousness … the shield of faith … the sword of the spirit."

But I really woke up in the prayers. A charming elderly gentleman, whom my parents had long known, proceeded to the lectern to lead us in prayer. I wish I'd paid more attention, for I cannot now remember how he led up to the fateful words asking God to help us in the fight against "the rise of secularism and the aggressive atheists".

"He's talking about me," I thought. I don't mean to be aggressive, and I don't believe aggression is called for, but I have certainly been dubbed one of those aggressive atheists before now. So it's to be a fight, is it? With us secularists as the "forces of evil", the "wiles of the devil". Are we to be countered with armour, breastplates, shields and swords?

This seemed to be the gist of the service. Coffee and tea being served in the smart new kitchen corner, I took my chance to ask him what he meant. And he meant it as a fight all right. But the really scary thing was what he thought we wicked secularists were up to – we apparently want to prevent him worshipping, destroy his faith and banish Christianity from the face of the earth. I explained that I don't want to stop him worshipping or destroy his faith. As a secularist, I am quite happy if people carry on with their religious practices as long as these do not give them special privileges in the affairs of state. As a humanist, I think we should rely on ourselves, not on an invented god. As an atheist, I would be delighted if people stopped believing in their various gods, and stopped believing their religion was right and everyone else's wrong. But I do not want to fight them over it unless they try to impose it upon the rest of us.

All this left me wondering just what I would fight over. I think faith schools are an abuse of children's precious minds and the last thing we need is more of them; I don't think bishops should have seats in the House of Lords. Unlike some humanists, I think we should follow the French and ban the burqa.

But really fight? Here on Cif, we were once asked, "Are there beliefs to die for?" And I replied that I would fight, and if necessary die, for women's freedom of the kind I have enjoyed all my life. I would certainly fight against the establishment of sharia law, and I should remember this when I say I don't want a fight. Yet these extremes are not likely, while the Church of England is all around us, and services such as this one presumably occur all the time. It is they, not I, who are girding their loins, taking up their shields and breastplates, sharpening their swords of the spirit and demanding a fight.

And they call me aggressive.