“The strongest argument in favor of the gospel is a loving and lovable Christian.” – The Ministry of Healing p 470.1
C. S. Lewis seems to be widely regarded as the modern father of Christian apologetics. Books such as “Mere Christianity”, “The Problem of Pain”, and “The Screwtape Letters” have strengthened the faith of many believers. Other writers, such as Ravi Zacharias, have contributed to a literature base that lend an intellectual credibility to Christianity. Books by these writers are valuable, but they are not the best argument for Christianity.
The best argument is rather a Christian who loves, and a Christian that is lovable. The books are useful, but books and logical arguments have never been good at convincing both mind and heart of the power of the gospel of someone looking into Christianity from the outside.
Proverbs 18:24 – A man who has friends must himself be friendly.
Christians should be loving. They should be patient, kind, and have an absence of pride, among other things. They should serve others from the pure standpoint of being glad to help the human family rather than hoping for something in return. They should be able to draw healthy boundaries to protect themselves and others.
Christians should be lovable. They should be friendly, warm, and consistent. Anything prickly in the character or personality should be overcome. They should be nice. Meanness and sharp tongues have never been virtues. Really, the qualities of being a loving Christian make one a lovable Christian.
These two aspects of Christianity together provide an argument, a line of reasoning, that make Christianity much more inviting than a logical train of ideas (not that those aren’t useful). Let’s keep both of these objectives in front of us today as we live our lives.
Laying Foundations 
Great advice.
Thanks! It takes perseverance and determination though. Loving isn’t easy.