Title VII also covers employment conditions and discharge. It prohibits religions discrimination in employment. Indeed it, or current interpretations of it, currently require employers to make reasonable accommodations for employees' religious practices.
As noted by an earlier poster, the homosexual organization that got this guy fired could also be in real trouble since they induced Allstate to fire him illegally due to his protected, off premises, religious activities.
Right - now define "reasonable".
And keep in mind that Title VII is applicable only if it does not impose an undue hardship on the employer. Now define "undue hardship".
My guess is that Allstate will argue, in response to the lawsuit, that the article in question will or could cause them to lose business among a targeted demographic (gays) and/or that it created a hostile work environment for their gay & lesbian employees. Those, among other defenses they will surely use.
Finally, guess who usually wins these things - the employer or the employee?