Why is anything associated with faith=irrational? Presbyterians and Methodists are amazingly middle of the road.
I can specifically speak to Presbyterianism -
It's based on the tenants of Calvinism. The church believes in doctrine based on the scripture and interpretation by local elders. There's no single authoritarian (unlike Catholics), it doesn't believe that the Bible is straight truth. It's perceived as a set of allergories which have to be examined and interpreted.
Presbyterians express their faith through actions, including education, pursuit of social justice and reform, and giving back to the community. (My church is very active in taking in refugees, building homes in our local town, as well as serving abroad to build hospitals, schools, etc..)
There is no need to confess your sins to a preacher. In church, you take a quiet moment to contemplate your confessions and offer them silently up to God to have them forgiven.
As for whether everyone goes to Heaven or not, God saved us all by the offering up of his only son. (Yes, I'm kidnapping Z and making him go to Heaven with me.
Baptism isn't done to prevent a child going to hell. It's done to show that God loves us before we can respond and show our love back. It's also a covenant between the members of the church and the baptized child, saying we will all work together to help bring the child up to be a good member of the church.
There's a lot of reading available at pcusa.org if you are so inclined. To sum it all up, this church treats you like a big person. You make your own decisions, you live the best life you can, but you are not bound by evangelical bible readings. There are many open points for discussion, and there is No One Right Truth. We all muddle through it together.
Oh, and...they're reasonable about abortion. Yes, a mainstream religion understands that it's a difficult choice and leaves it to the woman to make the best decision possible. ("We affirm the ability and responsibility of women, guided by the Scriptures and the Holy Spirit, in the context of their communities of faith, to make good moral choices in regard to problem pregnancies." http://www.pcusa.org/101/101-abortion.htm)
Beauty is truth; truth beauty - that is all ye need to know on earth...except TCP/IP.