There's a growing list of contexts in which many people think we should say little or nothing about God. Think of the radical redefining of separation of church and state and religious liberty in recent decades and the reaction to the intelligent design movement, for example. It's often considered too divisive, embarrassing, or whatever to bring up religious matters in school, in the workplace, in the media, or at family gatherings. The more that mindset is adopted in some settings, the more it tends to grow in others.
I recently heard somebody commenting on how Christians often use Facebook, Twitter, and other media to do things like post photographs of their children and discuss sporting events, yet say nothing about subjects like God and the Bible. I've been astonished by how many people's Facebook accounts are a form of evangelization for secularism. And that occurs even in nations where the large majority of people claim to be Christian. They have so much to say about their children and grandchildren, friends, music, movies, television, sports, their jobs, politics, travel, food, etc., but so little to say, if anything, about matters like God, theology, and apologetics. When people see something like your Facebook account, blog, or Twitter page, do they see a secular, or nearly secular, lifestyle?
You don't always know who your audience is or how much you're influencing people. If you live well, such as by speaking up about issues you ought to be speaking up about, that will influence other people to do the same. You don't know how much joy or encouragement you might bring some relative, former coworker, or somebody else who comes across your Facebook account or blog and sees you identifying yourself as a Christian or giving some indication of how much you've matured as a Christian. There are people who are looking for that sort of evidence where they want to find it, but aren't seeing it. I doubt that most people realize how damaging it is when so much of their life, including their online presence, is so secular.
"I am constantly astonished at people who say they believe in God but live as though happiness were to be found by giving him 2 percent of their attention." (John Piper, Desiring God [Sisters, Oregon: Multnomah Books, 1996], 268)