The Gospel today tells us God's true message to us, that He so loved the world that He sent His only Son to redeem the world. Many people deny God's existence, let alone His grace and His goodness. Some who are even on the fence about God, deny that Jesus was His Son. To me, one logically follows the other. If God is real (which He is) and He truly is a good and loving God (which He also is), then He would do everything in His power to save us, including sacrificing Himself. Thus if there is a just and merciful God (which there is), Jesus must be His Son.
Today's first reading makes the history geek within me a little giddy. Here we learn that God was willing to fulfill His promises even through the unbelieving emperor Cyrus the Great (of Persia). This is one of those points in the Bible that corresponds with non-religious historical writing (which was found well after people knew the Bible's version). Cyrus the Great is an actual historical person. We know that he made laws to support the ideas of religious tolerance and that he extended his influence from Persia to Egypt. In today's reading, he restores the Jews to their homeland after their long exile (a promise that God had made to them long before). He even helps rebuild their great temple in Jerusalem (as was also foretold).
God keeps His Word. Often, He uses the most unlikely of sources to do so. He is working through you as well, whether you believe in Him or not.