Does the Bible allow for true Christians to have a homophobic view of homosexuals, to mistreat and disrespect them?
Yes. It says to throw rocks at them till they die. That is both disrespectful and a great deal of mistreatment.
Then there are more modern interpretations of the Bible that say we should ignore that stuff about slavery, killing gays and disrespectful teens, no longer shun women who are having their period as unclean etc.
But they still consider it a "sin" of choice, when science is pretty clear that there is a genetic component to it and logic makes it pretty clear that they aren't harming anyone.
These modern Christians try to "cure" homosexuals and inflict an enormous amount of mental anguish on innocent teenagers in their misguided attempts to "cure" them of their very sexual identity.
These Christians are responsible for the suicides, depressions and mental health issues they are causing by their intolerant, ignorant and wholly indefensible beliefs.
But there are other Christians still who reject all of this, and while it doesn't make sense to me to cling to the religion and just pretend all its warts aren't there it's a great deal better than the fundamentalists who preach otherwise.
Still, there is no "respectful" way to tell a person that due to the sexual identity they were born with and developed they are "sinners" and especially no way to "respectfully" share the core belief that Christians have, that if you don't believe what they do you will spend eternity burning in Hell. That is simply not in any context a respectful position to take no matter how you sugarcoat it.
If you believe that rejection of Christian beliefs damns you to eternal hellfire that is fundamentally a harsh, disrespectful and rude belief to be sharing with others.