This passage is an excellent reminder of how quickly things can go wrong when we get frustrated with God's timing and decide to help Him along with His plan. His plan is always better. Always. His plan, His timing, His method. Not ours.
Abraham and Sarah decided to help God out because His plan didn't make sense to their finite minds, and got a lot of heartache in return for their efforts. Not just for them, but for their descendants. One bad choice had consequences that were unimaginably far reaching.
Any time we go against God's plan, we sin.
Our Romans passage reminds us that, as believers, we are no longer slaves to sin, but to righteousness. Of course, that doesn't mean we will never sin, but it will no longer master us. We will long to obey God out of gratitude and love for Him and all that He has done for us.
Romans 6:23 For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord.
The key to this verse is the word wages. Wages is something we have earned, something we deserve. We deserve death. But Christ's death enables us to receive something we do not deserve in the slightest - mercy, and eternal life. Thanks be to God for this glorious gift!
Tomorrow's Bible In a Year Passage passage: Genesis 18-19, Romans 7