Before you reply to a critic (either a Christian with a different view or a non-Christian) remember the following:
The person who has an objection to your beliefs (your theology or to Christian faith itself) is a human being in God's image. God loves them and values them. They deserve to be treated with kindness and respect. They are not stupid. Their motives may be good (in part, at least). Their objection may have merit and it certainly deserves to be taken seriously. Even if sin is involved in the objection and in their inclination to hold it, let s/he who is without sin cast the first stone.
If only we Christians would remember this a bit more often we would not be so rude, arrogant and, on occasion, downright nasty in the way that we sometimes handle doctrinal disputes between ourselves and in dealings with the likes of Richard Dawkins. I speak as one who also is liable to throw away a harsh remark about someone with whom I disagree (at least, if they are not around to reply).
So speaking the truth does matter but, as Paul said, speaking the truth in love. Without love truth is a weapon to wound rather than a balm to heal.