The Childcare Bill, if passed, will double free hours from 15 to 30 hours for 38 weeks a year - a total of 1,140 hours of childcare a year.
Speaking in the House of Lords on Tuesday, the Rt Rev Paul Butler said that the "impression increasingly created that a parent choosing not to work, but to raise their child themselves, is somehow not doing the best for the nation or the child".
He said the proposal, which was in the Tory manifesto seemed to champion "the adult first - their right to work, their economic well-being - rather than the child first".
And he added: "On behalf of the well-being of the children themselves, if we are going to make this increased provision, which I'm sure we will and should, let's try and ensure all the regulations that follow place the child at the centre, not the adults."
Ministers say up to 600,000 families will eventually benefit from the move, worth around £2,500 a year on top of the £2,500 they can already save from existing free childcare offers.
The scheme is planned to start from September 2016 and be fully implemented by September 2017.
