Come, and let us reason together.
— Isaiah 1:18
Be virtuous. Eliminate all vice. Perhaps the greatest cause of apostasy and error in Christian communities is the sight of hypocrisy. Strive to be perfect and loving in all things, lest your sin cause another to doubt the Truth of the Church.
Faith does not refer to certainty or evidence, but to trust in a trustworthy tradition. Many great saints wrote of feeling the absence of God. Recall that even atheists can pray, for doubt is a feeling—faith is an action. If you are struggling to overcome doubt and to build virtue, spend several minutes each day repeating the words of the demoniac’s father (Mark 9:24), the Jesus prayer, the Rosary, or the St. Thomas prayer (John 20:28). Seek out community, especially in your local parish. Teach and guide those who doubt to do likewise. Pray for friends, family, and coworkers whose doubt leads them not to pray.
Receive the Sacraments.
Participation in the Sacraments is essential for all praxis. Many in our modern world crave purpose, meaning, Truth, and Beauty, but find themselves lost. Invite friends, family, and coworkers to join you at Mass. Be persistent and kind. Gently chip away at the barriers which surround isolated souls and bring them into your parish community. The grace of the Sacraments can illuminate even the darkest of souls.
If you are well catechized, charismatic, or studied in Christian philosophy, engage in dialogue and debate with those who hold false ideologies. Do this both in relationships and at public events. Help remove their misunderstandings and barriers to accepting the Truth. In all apologetics, seek first to understand and then to be understood. Be kind, patient, respectful, and loving.
If you are well studied in, or a convert from, another religion or ideology, help discuss differences and present the Faith in a way that it can be clearly understood from another point of view. Seek to convert others by finding points of agreement and explaining the Church’s beliefs, both where they came from and why they are necessary to accept.