Organized religions are but a pointer to God, and they provide a pathway to seek holiness, but are not a substitute for God. Your friends are partly right; Christian religions do seek to train the mind. At first it is primarily because of threats and bribes (hell and heaven) but then it comes to returning the love that God gave us…
as in “… but most of all … because Thou art all good and deserving of all my love.”
Instead of telling them they are wrong (there are plenty of negative examples to support their view) try telling them, “I understand why you might feel that way, considering what you’ve seen and heard, but there is a deeper faith that is really quite liberating.”
Jesus’ teachings are very liberating. And that applies whether you believe He was actually God incarnate or not. His teachings help us understand how to behave when under the thumb of oppressors, and how to keep our minds and hearts free of despair even when we are under such control. The spiritual journey leads us to emotional stability, and contentment in life.
After 8 years of Catholic grade school and faithfully attending Mass until I went away to college, I was never inspired to actually purchase a Bible. That was a result from watching a particular TV preacher (NOT Jimmy Swaggart or Jim and Tammy Faye

) who showed me – perhaps unwittingly – that the wisdom in the Bible is so profound that even though I had my doubts about God’s existence, I saw that the Bible could help me get over some issues. In fact, his explanation of how faith works, had a striking parallel to a guy selling audio tapes for “self-talk” for $300. I thought, “well this guy is teaching me essentially the same thing, except using different vocabulary – one talks about the subconscious, the other about God the Father, Son, and Holy Spirit… but mechanically they are the same … so do I spend $300 to listen to the one guy, or $11.95 to listen to the other?” Over time, and after a good amount of Bible study, the wisdom and truth in Jesus’s teachings became self-evident and I began to believe in their authenticity.
Listen to them, set aside the urge to immediately counter everything they say, and really hear them out. Ask them about their experiences that lead them to these conclusions. Listen first, then if the time is right, offer some of your own comments. Use their own concerns to base your next move. If they feel religion is oppressive, say, “I can understand you now, based on your experiences, and why you might feel the way you do … personally, though, I have found it to be quite liberating. I feel a meaning and purpose to life, and I have greater emotional stability and less fear.”
Quoting sources they don’t believe in, without a good reason (one that makes sense to them where they are now) is not likely to change their minds. Empathize with them. Hear them out. Acknowledge their feelings, instead of dismissing them as being misinformed. Show them that you’re not just trying to brainwash them, but to help show them a way of True Freedom so that they may live their lives to the fullest. Otherwise if you keep saying, "but see it says here in the Bible that … " followed by something that makes no sense to them, you might as well be a Jehovah’s Witness, annoying people who have no interest in the gobbledygook they are spouting. I’ve been there. Like I said, it was not somebody insisting I believe this or that [abstract idea with no apparent usefulness] or go to hell that got me interested; it was a person who showed me that there was something in that Book that could help me here and now, doubts and all.
I’ve heard, “people don’t care what you know until they know that you care.”
Then let the Holy Spirit take it from there. If you truly “feel their pain,” you will be in a good position to recognize what sorts of arguments they might want and need to hear in order to make progress, and they will be more receptive to hearing you.
Alan