According to the New Testament, who are 'nonbelievers'? Are they members of organized religions?

Hebrews chapter 4 mentions nonbelievers and believers and rest on the 7th day seems to be the difference. In verse 6 is says some did not enter in because of unbelief. Verse 11 tells us to enter into that rest least we fall into unbelief. According to verses 7,8 tells us a certain day is limited for it and Jesus never spoke of another day so it remains. According to Matthew 28:1 The 1st day begins right after the Sabbath that Jesus rested in the grave over. Amazing Facts with Doug Batchelor has some great online Bible studies if you have more questions. Thanks for a great question!