It's not hard to find people who have some way ignored, explained away, forgotten, or twisted the Sermon on the Mount. I'm not going to slay these men with my words, but plead with them to reevaluate their positions, reevaluate your position, and to look for the historic faith. What are the practices and positions of the early Christians? You can't ignore them when there's 300 years of unity in the early church. They all basically practiced the same way.
Clement of Alexandria says, "We should be praying for those not against these brothers, although they are not currently brothers, but we don't know if they will be, and we should act as if they may be our brothers one day." And another early Christian said, "They are not to be enemies of man, but enemies of his era."