I recently wrote about the free gift of salvation that God has given us. The gift of everlasting life is free to us, but cost Jesus everything. He paid the bill through His sacrificial death and resurrection.
But while the gift of salvation is free, this does not mean that there is no cost to being a follower of Christ. So many want to live the Christian life without any sacrificing or any giving, but there's more to it than that. For instance, in saying "Yes" to Christ, we're saying "No" to much of what the world around us has to offer.
Another "cost" that Christians should – must – pay is associated with reaching the lost; those who haven't yet recognized their need for a Savior and are still living life on their own terms. If you look at Luke 15:8-10 you'll see what I mean:
"Or suppose a woman has ten silver coins and loses one. Doesn't she light a lamp, sweep the house and search carefully until she finds it? And when she finds it, she calls her friends and neighbors together and says, 'Rejoice with me; I have found my lost coin.' In the same way, I tell you, there is rejoicing in the presence of the angels of God over one sinner who repents."