On the cross, facing imminent death, unthinkable pain, and... of course, the judgment for my sin and yours, Jesus looked out with compassion upon those at the foot of the cross. Some were crying, but most were not. Most of them begged and pleaded for Him to be on that cross, and at the time when Christ was on the cross they were cursing Him, blaspheming Him. They hated Him without cause and they really didn't know what they were doing. They didn't believe that Jesus was their Messiah. They certainly didn't believe that He was God in the flesh. They simply did not know they were killing the Source of Life. They didn't know they were shaming the Prince of Peace. They really didn't know. That brings me to my point.
When Jesus prayed, "Father, forgive them, for they don't know what they are doing," that was a very specific prayer for a specific group of people at a specific time. The problem is that many modern Christians act as if it's a part of the Lord's Prayer and use it as a blanket supplication for all people for all their sins for all time. It wasn't prayed in that context, and it's not applicable most of the time. A popular Christian band recently released a song using this prayer just as I have described. It's catchy, I guess.
Here's why this prayer is being misused most of the time: Humans, for the most part, know when they are sinning. God has given humanity a conscience, and has sent His Spirit into the world to convict us of sin, righteousness, and judgment. So, it's just untrue to pray, "they don't know what they're doing." They know…
See, when Christ prayed this prayer He was asking the Father to forgive those at the cross because they didn't know they were crucifying and cursing the Son of God. Now, we can certainly apply this when we pray for our unsaved friends and family for their disbelief. But to pray for someone who is committing adultery or stealing from the till at work and ask God to forgive them because they don't know what they're doing is flat wrong. Pray that God convicts their heart and that they respond. Pray that they repent and RUN from sin. But don't pray that God forgives them (because they don't know what they're doing). They know.
Stepping back off my soapbox and running for the back door. Do not pursue. I am faster than you.