If your driving passion in life is to speak truth to a cause, then by all means, do so. Just understand that you will have to navigate your ship accordingly. If you are extremely conservative, believe that homosexuals should not have the right to be married, and so on, and not only convey that in your writing but also in your public persona, fine. Understand that you won't get your foot in the door with a very liberal agent from San Francisco whose best friend is a lesbian whose marriage was just disallowed by a state law that you backed (hypothetical, I have no idea if this person exists).
You'll also have a hard time reaching those in the middle of the road because they're not going to want to rock the boat. And depending on how you've portrayed yourself, you may have made it easier or more difficult to sell your work. They might perceive you as being difficult to work with because you come across as being so headstrong.
I guess I just look at it differently than most. I'll admit, I was getting very riled up and outspoken with the last election cycle. I spent hours researching my points, seeking the truth. Trouble was, no one else paid any attention to that truth. In the end I was left with a lot of anger and resentment.
That's when I turned back to fiction. I realized that I was so much happier dumping myself into the cause of good writing. I could tell my stories, show people the possibility of a better world through my words without trying to hammer it into their heads. At the end of the day I came away from it satisfied. I wasn't angry or fed up or left feeling helpless. I felt content.
For me, my biggest drive is to have my words read. I'm not going to change my message or beliefs in order to make that happen, but I will accept that I am trying to take on the role of an entertainer, not a politician or activist. Until I can make my own rules like Card and others, I'll keep quiet and let my stories do the talking.
So please, speak truth in your words. Just be sure that your words get heard. Otherwise, you end up speaking the truth of silence and those who knew how to play the game get to inundate the rest of us with their views.