It is permissible to play football. As for supporting a football team, it is permissible on condition that you do not insult the followers of the rival team, harm them and dislike them. It is haram to do something to a Muslim brother that Islam forbids like insulting him and being angry with him. It is necessary to be very careful about it because it is the point that is abused the most. Sometimes, a person insults the players and supporters of the rival team when his team concedes a goal.

It is not permissible to do all kinds of deeds and to utter all kinds of words that are contrary to Islam. It is necessary to avoid them even if you are joking. 

The religion of Islam is against all kinds of bad deeds and hurting people because Islam tries to make man a real man. Islam elevates man to the level of real humanity. Therefore, Islam gives orders that will lead man to all kinds of perfection and beauty; it forbids the deeds that lead man to disgrace and heinousness.

Acting upon this general rule, we can say that all kinds of deeds like swearing and cursing that offend and disturb people are sinful and haram because it is haram to offend people and it makes a believer a sinner. It is forbidden to disturb even an unbeliever if he is innocent because the Prophet (pbuh) said, “I am the enemy of any person who maltreats a zimmi (a non-Muslim subject living in a Muslim country).”

It is definitely haram to bet and gamble on football games.