Welcome with open arms fellow believers who don't see things the way you do. And don't jump all over them every time they do or say something you don't agree with - even when it seems that they are strong on opinions but weak in the faith department. Remember, they have their own history to deal with. Treat them gently.
For instance, a person who has been around for a while might well be convinced that he can eat anything on the table, while another, with a different background, might assume all Christians should be vegetarians and eat accordingly.
But since both are guests at Christ's table, wouldn't it be terribly rude if they fell to criticizing what the other ate or didn't eat? God, after all, invited them both to the table.
Do you have any business crossing people off the guest list or interfering with God's welcome? If there are corrections to be made or manners to be learned, God can handle that without your help.
Or, say, one person thinks that some days should be set aside as holy and another thinks that each day is pretty much like any other. There are good reasons either way. So, each person is free to follow the convictions of conscience.
What's important in all this is that if you keep a holy day, keep it for God's sake; if you eat meat, eat it to the glory of God and thank God for prime rib; if you're a vegetarian, eat vegetables to the glory of God and thank God for broccoli.