We must respect the other fellow's religion, but only in the sense and to the extent that we respect his theory that his wife is beautiful and his children smart
- H. L. Mencken

It ain't the parts of the Bible that I can't understand that bother me, it is the parts that I do understand
- Mark Twain

If god created my brain I'm certain he approves of its usage
- Nogard

Interstingly enough, I have found that the prayers I offer to the sun and the prayers I formerly offered to God ar all answered at about the same 50% rate
- George Carlin

When a man is freed of religion, he has a better chance to live a normal and wholesome life.
- Sigmund Freud

There must be Religion. Otherwise the poor would murder the rich.
- Napolean Bonaparte

"Religious suffering is at the same time the expression of real suffering, and the protest against real suffering. Religion is the sigh of the oppressed creature, the heart of a heartless world, just as it is the spirit of a spiritless situation; it is the opium of the people. The abolition of religion as the illusory happiness of the people is required for their real happiness. The demand to give up the illusion about it's condition is the demand to give up a condition which needs illusions." - Dr. Karl Marx

So if we get rid of religion, what shall we replace it with?

You took the quote literally, and it isn't meant to be read that way. Nobody can "abolish" religion. It simply suggests that once this crises-ridden mode of production meets it's final "recession", it corresponds, that a new society will be forged in it's place. And one with much more humane / rational social relations, as well as more efficient means of production (given the immense impetus given by capitalism before it). In a new society, one can only imagine, that as life becomes a little easier, most people won't need religion & superstition anymore. In fact, we need not even go that far. They say that today two currents are especially growing world wide - Islam & atheism. The reason for the former's growth I can only speculate, but it's colossal growth, with time, can only succumb to science. Much like the Bible, these books are being refuted by science daily, but followers of religion refuse to accept facts, and there is a reason for this. You can try to inject all the sense, logic & reasoning into a religious person, but few will actually listen to you(I speak for myself, your experiences may have varied). They cling to religion for dear life because it gives them hope, strength, & purpose. I am 27 years old today, however when I was 11 / 12 / 13...I was a Roman Catholic, and I remember what it was like, and how I used the religion I was brought up with, in my troubled youth, to garner strength. It can be very powerful, and it will not evanesce as easily as that, for there is a reason religion is still so popular, especially in places like the middle east, Africa and Latin America, which is home to the highest concentration of Christians in the world, particularly of the Catholic sect.

...however, when you talk like that(like me), so many people accuse you of being "utopian", yes, that is what they say, right before picking up the bible and reading from Corinthians(in hopes of earning brownie points from an 'omnipotent' divine tyrant who lives in the sky), or faithfully placing their vote in a ballot box, in the hopes of helping ascend some fraudulent / megalomaniac / narcissistic bureaucrat to power for some given amount of time, to "better" society & the world. I wonder what kinds of thoughts haunted the citizens of the Roman Empire, as it crumbled around them, or any citizen of the Ottoman Caliphate, for that matter. As decadent as it was...I doubt anyone actually really thought it was really going to happen. Jehovah / Yehweh will pass...like Jupiter / Zeus did...hello dialectics.