Sporting authorities should take a "zero tolerance" approach to homophobia, with immediate and lengthy stadium bans for fans who hurl anti-gay abuse, MPs have said.
Attitudes towards gay, lesbian and bisexual (LGB) people within sport - and particularly football - are "out of step with wider society", said the House of Commons Culture, Media and Sport Committee in a hard-hitting report.
The MPs said they were "particularly disturbed" by the inclusion of boxer Tyson Fury on the shortlist for the BBC's Sports Personality of the Year in 2015, despite his history of homophobic comments.
The committee said it was "very dissatisfied" with director general Lord Hall's defence of the decision, which raised questions about the judgment of BBC executives.
Citing surveys which suggested that 72% of football fans had heard homophobic abuse at matches, the committee said it was "concerned" language of this kind was not taken seriously enough and was too often dismissed as "banter" despite its damaging effect.
It warned it was "unacceptable" for sports coaches and managers to allow homophobic comments between players in the dressing room to pass "without comment or redress".
Clubs should treat such language as severely as racist behaviour, the cross-party committee said.
The report praised the two-year ban handed out to rugby fans who directed homophobic abuse at international referee Nigel Owens as an example of "good practice" which should be followed by other sports.
Football clubs in particular were "not doing enough" and should take a tougher approach, including one- and two-year bans for fans' first offences. Match officials should have a duty to report and document any homophobic abuse, whether from professional players in a top-tier match or parents on the touchline of a youth game.
The report hailed openly LGB sportspeople including diver Tom Daley, rugby's Gareth Thomas and footballer Casey Stoney as role models who had given "great help and comfort" to young people coming to terms with their sexuality.
But it voiced "great concern" that - while the UK's team at last year's Rio Olympics included 44 "out" athletes - there was not a single openly gay footballer in the men's professional game.
Football has a "problematic" history with homophobia, with anti-gay chants "relatively commonplace" at games and homophobic leaflets reported to have been handed out outside West Ham United's ground in 2016, the report said.
A number of sports were being "robbed of talent" because of the significantly higher drop-out rate among LGB youth, it warned.
The committee called for sporting bodies to fund anti-homophobic campaigns with ads on display screens at matches, as well as on TV and in cinemas.
And it called on sportswear brands to demonstrate their support for LGB athletes by including clauses in sponsorship agreements to make clear that contracts will not be downgraded or terminated if a player comes out as gay.
Committee chair Damian Collins said: "From the evidence we have received in this inquiry, we believe that there are many gay athletes who have not come out, because they are frightened of the impact this decision will have on their careers, and the lives of the people they love.
"That is not acceptable and should not be tolerated.
"Coming out is a personal and private decision and no sportsperson should feel under pressure or feel forced to come out, but sports authorities must create an environment, in the stadium and the locker room, where players and athletes at all levels feel it is a choice they can make, and that they will be supported and accepted if they do."
A Football Association spokesman: "We welcome the select committee's report on how to address homophobia in sport and we will review it in full.
"It is an issue that we take very seriously and, as the chairman has previously stated, tackling homophobia, transphobia and biphobia in football is one of his top priorities."
A BBC spokesman said: "The British public decides who becomes Sports Personality of the Year.
"A panel of experts in sport unanimously agreed that Tyson Fury should be on the shortlist for the public vote based solely on his sporting achievement in being crowned World Heavyweight Champion - we were clear it was not an endorsement of his personal views."