Christians, how are people supposed to tell whether Christianity is the most true faith or not?

It seems it really depends upon how philosophical each person eventually becomes after experiencing life in their early years. For those who truly question why they exist and the purpose of life, you would think that any religion that bases its teachings upon those basics could not be ignored. One should be able to use their natural reason to determine the existence of God as a supreme spiritual Being who really has no NEED to create. But creation does exist. This should force one to conclude that God does it for His own honor & glory requiring worship which God still does not really need. If he picks up scripture, he will discover that God made mankind into His Own spiritual image of self awareness of knowing (intellect) and acting (will). This means that God shares (love) His existence with us. Hence, man should now conclude that God made man to know (intellect), love (will) and serve (WORSHIP) God in this world and to be happy (SHARE) with God forever in heaven. Thus the real reason for creation is love (Almighty God). So which religion arrives at this TOTAL conclusion as the real reason for our creation? Are all its teachings designed in this fashion?