Someone asked this question the other day - if sex before marriage is a sin, does that make a child conceived before marriage a sin?
Short Answer: NO. To elaborate...
All children are blessings and gifts from God. I was in a really bad place in my life - partying, drinking, smoking... sex...
God protected me - he kept me from getting pregnant by a guy I was with for 2 years, in a psychologically abusive relationship. My step-dad and a lady at our church literally prayed for God to close my womb, and I believe wholeheartedly that is what happened. It is the ONLY explanation. (Refer back to my personal testimony post for detail.)
As soon as said guy and I finally broke up, they stopped praying. That section of my life was over. A few months later I met a new guy - head on his shoulders, in college, job, etc. A step up actually... LOL. God knew how the whole thing would play out. He knew this guy didn't want kids and that it would be the best opportunity for him to step into my sinful life and give me this gift, that he knew would inevitably open my eyes and turn me around.
The sex was my sin. The baby was my gift. I got pregnant, and this guy didn't want anything to do with either of us. I was scared to death. Abortion was NEVER, EVER an option. And I knew I couldn't possibly give my child away. But this pregnancy is what drove me to Georgia. It was what got me to a place where I could feel accepted and find God. It was drove me to the place where I met my wonderful husband. And my son is a gift from God, meant to lead me back to a better place in my life.
So to end this post, the answer is no - Children are not a sin, they are a gift. My child is not a bastard, he is a blessing. He makes me stronger. God loves him, and me. He has forgiven me for my past transgressions, and given me a wonderful reason to grow stronger with him every day.