nah it was never founded secularly. every politician from its beginnings would attend a church on sundays. just the fed would not infringe on church affairs and themso to the fed. just because non religuous immigrants or atheists are flooding the country doesnt make it not religious. that is why i use still. there is a reason most politicians are in the jewish paybook(aipac), they themselves are religious and supporting fellow religious people albeit at the expense of the people.  back to say colonies. take plymouth, nearly every citizen was a puritan. everybody is and was religious. you cpuld probably ask most "atheists" alive now and youd hear them say they probably grew up religious and just arent anymore. very few have never practised faith in some fashion.
United States