The church mostly fails at sharing the Gospel today.  They avoid mentioning any unpleasant facts like sin and the judgment of God.  If people don't know what they need saving from, they won't submit to a savior

Also people witness today in the same way they did 50 years ago when America was a Christian nation and everyone knew the Bible and most liked Christian principles, even if they weren't true believers.  They had the foundational knowledge to understand the Gospel message.  Today, most Americans either don't know anything about the Bible or most of what they think they know is false.  They don't have the foundation necessary to understand the Gospel message.  They don't know who God is.  They don't know what sin is.  They don't know why they deserve judgement.  Without giving them this foundational knowledge, they can't understand the message, "You need the Savior."

As Christians we have failed to live Godly lives that set us apart.  As Christians we have failed to share the Gospel message.  As Christians we have failed to share the foundational message of our sin nature and the creator God who is owed totally allegiance because we owe Him for every breathe we take.