The one thing that defines us as Christians is our relationship with Christ. As Catholics, we have the sacraments to enhance that relationship, facilitate its growth, and to bring it back to life when it has died through serious sin.
The divine revelation given to us by Christ is that God is love and desires to love us in a deep and intimate way. He is not a God of vengeance and retribution, but wants all people to experience His love. We are the primary dispensers of His love in the world. We are created to be a wellspring of His love, which we receive from Him and allow it to pour forth from us to the world.
Consequently, in our journey of faith we have to continually evangelize ourselves to be open to His love and mirror His image to the world by loving one another to the best of our ability. This journey of faith has many hills to climb and dark valleys to travel through, but we strive through these trials to seek out His strength, His peace, His hope, and His consolation, so as to always grow closer to Him and consequently, become more open to His love.
Our work of evangelizing the world then is filling the world with His love, peace, joy, and consolation. We are not called to exterminate those who live as if there is no God, but to transform them by His love. We are called to show them the goodness of Christ and the benefits of being in relationship with Him. So the primary evangelizing message is God loves you beyond anything you can imagine.