While the president often refers to God during public addresses to his supporters, Bush's religious convictions don't always seem to reflect those of the conservative Christians who make up his political base.
In an exclusive interview with ABC News' Charles Gibson, Bush said he believes that both Christians and Muslims worship the same God.
"I think we do. We have different routes of getting to the Almighty," Bush said. "But I want you to understand, I want your listeners to understand, I don't get to get decide who goes to heaven. The Almighty God decides who goes to heaven and I am on my personal walk," he said.
When it comes to Osama bin Laden and Abu Musab al-Zarqawi, who both claim to be devout Muslims, Bush says he believes they are misguided.
"I think they pray to a false God, otherwise they wouldn't be killing … like they have been."
Bush says he doesn't believe the United States is in a religious battle when it comes to the war on terror. He says he wants to make it clear that America is fighting against groups of people who want to kill innocent people and not groups looking to practice their religion.
"I don't think this is a religious war. I think this is a war between evil people that are willing to kill on a mass scale; people that would like to end up with weapons of mass destruction, even kill more than they did in New York City and Washington, D.C."
While President Bush is pretty clear-cut when it comes to his feelings on the war in Iraq, taxes and health care, when it comes to the motivation behind his own stand on same-sex marriage, the president seems more willing to leave room for a deeper discussion.
Bush told Gibson he's not sure if homosexuals are born with sexual preferences or whether those preferences develop later in life.
When asked to look at the topic from a nature versus nurture standpoint, Bush said that he's open to the possibility that nature could be the defining component when it comes to a person's sexual preference.
Meanwhile, Bush says he has not changed his ideas on what constitutes a legal marriage.
"I view the definition of marriage different from legal arrangements that enable people to have rights. And I strongly believe that marriage ought to be defined as between, a union between a man and a woman," Bush said. "Now, having said that, states ought to be able to have the right to pass … laws that enable people to you know, be able to have rights, like others."
Bush, who supports a constitutional amendment that would define marriage as a union of a man and a woman, says he's concerned about what activist judges will do without clear guidelines.
"Look. If you're interested in preserving marriage as a union between a man and a woman, there is one way to do so, without the courts making the decision. That's through the constitutional process and obviously I think that's the way to go, because I am concerned that courts are making this decision. This is too important a decision to have a handful of judges making, on behalf of the American people," Bush said.
While Kerry has said he opposes same-sex marriage, he does not support a constitutional amendment.
When asked her thoughts on a constitutional amendment, first lady Laura Bush said she sees it as an issue that people want to talk about.
"I'm not really sure about it. I think it's important to have the debate," she said.