(Community Matters) Tx GOP Platform includes:
“We affirm that the practice of homosexuality tears at the fabric of society and contributes to the breakdown of the family unit.
Homosexual behavior is contrary to the fundamental, unchanging truths that have been ordained by God, recognized by our country’s founders, and shared by the majority of Texans. Homosexuality must not be presented as an acceptable “alternative” lifestyle, in public policy, nor should “family” be redefined to include homosexual “couples.” We believe there should be no granting of special legal entitlements or creation of special status for homosexual behavior, regardless of state of origin. Additionally, we oppose any criminal or civil penalties against those who oppose homosexuality out of faith, conviction or belief in traditional values.”
We have LOTS of Tx Republicans who support us and don’t think like this. And, many continue to work regularly at making new friends from both sides of the aisle. We know others must be won over one at a time. And, when you think about it, we’ve not done too bad. When I was on the HRC board in the early 90s (when we started polling on this), I doubt we had 20% support. Today, 51 – 53% of Americans believe we should even have equality in marriage. Nearly three quarters now support other LGBT rights. And, despite further to go in Texas, we’ll eventually prevail. Glass half full or half empty? I’d say nationally it’s 3/4 full; statewide, we’re approaching half.
Community Matters 
When was the last time the Republicans did not win a statewide election in Texas? They are so much the dominant party now they can put pretty much anything in the platform. Very few voters pay attention to party platforms, and as you say, plenty of loyal party members disagree with sections of the platform.
If the Republicans thought they had a chance of losing an important office, they wouldn’t stick stuff like that in there.
The problem in Texas isn’t that the Repubs are backwards; it’s that the Democratic party is so weak. Even when the Dems come up with a good candidate (e.g. Bill White) running against an incumbent everyone is sick of (Perry), it isn’t even close.