1 Corinthians 7:17-24 starts with a really straight forward command, "...each person should live as a believer in whatever situation the Lord has assigned to them, just as God has called them." Step 1 of being a Christian: live as a believer. What? Are you serious?
Now, this is not actually "Step 1", I'd say faith is, but how often are we actually living as though we are saved from our Sin by the God of the Universe? Salvation is from eternal death, pain, torture, and separation from God? Are we living like we understand the grace that has been given to us? We don't deserve to be forgiven of our sins, but God has given us Jesus as payment for our sins.
When we are saved, we aren't called to take ourselves out of the situation we are in. And we are not called to make drastic changes (like circumcision) to ourselves. Outward physical changes are not what living as a believer is about. Verses 19-20 "...Keeping God’s commands is what counts. 20 Each person should remain in the situation they were in when God called them."
The last section of this passage talks about whether the believer is a slave or one who is free. For the slave, he is not to worry, unless he can earn his freedom. I'm not really sure about this section, or how to relate it to our society today, but I know that we are not to enslave ourselves to any thing or any one. We are the Lord's slave, because we were bought by His blood. When He paid for our sin with His life, He called us to serve Him. As believers we should live as such, by expressing the freedom from sin and its consequence (eternal separation and death) we have in Christ.