believing the word

you know you really believe when you are fully convince of the promises of god rom.4:20-21 like abraham was fully convince that he didn't even waver not even his age made him doubt gen.21:5 says he was 100 yrs old sarah was90 yrs gen17:17 thats why he was call the father of faith if we don't believe we don't receive we have to believe his promises like our father abraham did.it is not only believing in god but believing god's word.