Do you want to be more devout, but believe your past is holding you back?
Or are you happy with your level of involvement, but you are afraid to tell him, because of what his reaction might be?
If the first, then I suggest speaking to the vicar, or someone in the church, to work through that.
If the second, then religion makes no difference. If he would judge you, and hold your past against you, then perhaps he's not such a great husband for you. (Although, he may need some time to process what you tell him, which would be fair enough.)
As to whether you feel you should tell him, I personally don't there has to be no secrets between a married couple. I think sometimes it can be useful to tell a partner about certain things from your past, though, because they have helped to shape the person you are now.
Maybe your DH is someone who believes there should be no secrets between a married couple, though, in which case he would feel you have betrayed him. Which I guess is a risk you would take, in telling him, now.
The thing is, marriage, particularly within the context of a religious ceremony, is supposed to be forever. Can you, and do you want to, keep this secret from him "til death do us part"?