There is already value without God. Kant derived moral judgements on purely secular bases 200 years ago. The "deontology" he ushered in is now the single most common ethical view held by philosophers today (25.9% according to Bourget & Chalmers 2013), and Kant scholars are at pains to teach it to students and anyone else who would listen.
The problem for many people is they suppose that determining what is wrong and what is right must be easy. Why think this? Why should it be easy? Do you fully understand Wiles' proof of Fermat's Last Theorem? Probably not, but he gave it. Do you fully understand Kant's deduction of the categorical imperative in particular and his deduction of the possibility of synthetic a priory judgements in general? Probably not, but he gave them.