To make this more real, let's look at one practical application:
I like beer, wine, and various other alcoholic drinks. I also like the flavor (and effect) of coffee. There are people for whom alcohol is a stumbling block. I once was so addicted to coffee that I could not live without it. Now, I can take it or leave it. I can drink, or not drink. If I am with someone that does not drink alcohol, I do not drink either. I know there are many who are still addicted to coffee, alcohol, or other things. The grace is passed by allowing others to make their decisions as to whether they will drink alcohol or coffee or not. I do not believe there is anything wrong with drinking either one in moderation. However, if there is anyone who has a problem with drinking, or thinks it is wrong, I do not drink around or with them. Nor do I bring up matters of conscience by talking about drinking around them.