Unfortunately very serious sin - mortal sin - "kills" our friendship with God. By willfully committing mortal sin, we reject God, and we lose this sanctifying grace (Titus 1:16).

We can know what sins are considered mortal from Holy Scripture; from the teaching of the Church, and from the writings of the Fathers and Doctors of the Church.

Our fallen world does not want God’s presence or grace. It is content to swim in its own cesspool and convince itself that things are okay. Such a mentality has no tolerance for prayer.