"When I came to you, brothers, I did not come with eloquence or superior wisdom as I proclaimed to you the testimony about God. For I resolved to know nothing while I was with you except Jesus Christ and him crucified. I came to you in weakness and fear, and with much trembling. My message and my preaching were not with wise and persuasive words, but with a demonstration of the Spirit’s power, so that your faith might not rest on men’s wisdom, but on God’s power."
- 1 Corinthians 2:1-2
Preaching anything first through logic or reasoning will only result in people trying to make themselves better apart from God. They need to know and hear that the only way to God is provided by the sacrifice that Jesus made for them on the cross. There is no amount of striving to be better on our own without Jesus' sacrifice that can bring us to God. Any goodness evident in mankind is the result of God's goodness. (James 1:17) The Incarnation is important, but it's not the teaching that will demonstrate why we need Jesus. God's love is wonderful, but the misinterpretation of what "love" is in our day leads to all kinds of confusion and teachings that do not accurately represent God's love. The cross is what we need to teach first. It is the core teaching of the gospel that leads us to a right understanding of all the other teachings. It is the demonstration of the greatest and highest love, the reason we are able to have new life, and welcomed into God's family as his children.