please look to ROMANS 14. this entire chapter covers what one man might deem holy another may not. i believe the contex of it is more than food and holy days. for example my sister asked me if smoking was a sin, i asked her "do you think it is" she thought awile and said yes, i then told her then it is for you but may be ok for someone else. this applies to grey areas of the bible where we are not sure of gods word on a particular subject. somethings can be a sin for one person but not another. when you are not sure dont grieve the holy spirit. please pay special attention to verse 22 and 23 in Romans 14. Christ is our lord not man and his personal ideas and taboos. if your walking in spirit you will find out at some point if you made a bad decision and be convicted, the holy spirit will see to it.