More importantly, let's tie this to housing discrimination. The cake decision is based on:
Justice Clarence Thomas, in an opinion joined by Justice Neil M. Gorsuch, accepted this argument and said that forcing the baker to make a cake would be impermissible compelled speech. He wrote: “Forcing Phillips to make custom wedding cakes for same-sex marriages requires him to, at the very least, acknowledge that same-sex weddings are ‘weddings’ and suggest that they should be celebrated—the precise message he believes his faith forbids. The First Amendment prohibits Colorado from requiring Phillips to ‘bear witness to [these] fact[s],’ or to ‘affir[m] . . . a belief with which [he] disagrees.’”
Now, here's where the bible stands on homosexuality:
The Bible says: “Men who practice homosexuality . . . will not inherit God’s Kingdom.” (1 Corinthians 6:9, 10)
It seems that renting half your duplex, and witnessing this sin day in and day out, would be more of a sin than baking a cake for a wedding.
If you want to really complicate this matter, look to conscientious objection to military draft, or even paying taxes that support a defense budget. This is EXTREMELY more complex than the few nonsense posts here have even touched on.