Uh, sorry, but no. Each person has responsibility to make their own decisions. By our efforts or decisions we cannot make a decision for someone else. If that were true, there would be no reason for evangelism, just prayer meetings. We could say a prayer on someone else's behalf, or get baptized for them by proxy, and, DEAL! There is no Scripture to support those ideas, but there are Scriptures to say that it's each person's own decision.

Salvation is based on a love relationship with God, submitting to his Lordship, and inviting him to do a miracle in you to change your nature from a sin nature to the nature of Jesus. So your situation shows three strikes:

1. Your dad wouldn't have a love relationship with God because you prayed. He has to choose to love and live in that love.
2. Your dad wouldn't submit his life to Christ because you pray for him. That's an action he alone can take.
3. Your dad has to invite Christ into his life. You can't invite Christ into his life for him. It's an action he alone can take.

Okay so a little back story... I grew up as an agnostic. My mom was raised Catholic but doesn't believe Jesus is the only way to salvation and is pretty liberal about it all. My dad was raised Muslim and is semi-practicing, but definitely believes Jesus was not God. His entire family lives in the Middle East and are all committed Muslims.

Does God save people's souls—even if they're an unbeliever—by another believer's prayer? I don't see any way that I could get my dad to believe in Christ, mainly because he would have to acknowledge that his deceased brother, as well as the rest of his family, will go to hell because they believed in a lie. Basically, my dad will never be a Christian from what I know about him, but can my prayer be the source of their salvation? I understand that ultimately everybody is responsible for their own salvation, and nobody can make up their mind but them. Does God make exceptions for his believers?