This is not insulting to anybody. It is offensive. Our Lord and Savior Christ Jesus as the only mechanism for the Kingdom of Heaven is probably the most offensive thing imaginable to the human mind. Nevertheless, it is true and veritable.
If your father, grandfather, and several uncles exercise faith alone in Christ alone, I rejoice for their faith in glorification of the Son. Like I previously mentioned, the environment doesn't preclude faith in Christ. The community which denies Him, will bear bad fruit.
Where do you get your false information?