The bishops said their position was based on the denomination's view that "war is incompatible with the teachings and examples of Christ", and Jesus Christ's call for "his followers to be peacemakers". President George W Bush is a member of the United Methodist Church.
There have been 3,954 US deaths in Iraq, according to the Iraq Coalition Casualty Count, and over 28,773 wounded, according to Global Security.org.
Currently, the US is in the process of withdrawing 22,000 troops, which will be completed in July.
On Monday, US Defense Secretary Robert Gates told reporters in Baghdad during his unannounced visit that a pause in the withdrawal of US forces from Iraq after the current reduction "makes sense", according to CNN.
US commander in Iraq, General David Petraeus, is said to believe that a careful review is necessary before any decision is made about further troop withdrawals. Petraeus is scheduled to come to Washington in April to brief President Bush and Congress about the situation in Iraq.
The Iraq war has had a detrimental effect on the country's small population of Christians. It is estimated that Christians make up nearly half of all refugees leaving Iraq, although they make up less than three per cent of the country's population. There are only about 600,000 Iraqi Christians left in the country, down from 1.2 million before the 2003 US-led offensive.
Persistent instability and violence in Iraq has also led to increased attacks on Christians. Last month, 10 churches were bombed within two weeks. Christians are also the target of kidnappings, mostly for ransom money.
Overall, the majority of evangelical leaders support the war, but almost as many expressed serious reservations, according to the NAE survey.
"I am also very concerned that the ardent support by evangelicals for the war in Iraq, and unquestioning support of President Bush has made evangelicals appear as if we are 'pro-war'. The increasing battle cry among evangelicals to fight radical Islamists is also troubling to me," said one leader.
Other concerns of evangelical leaders include the damage to the image of America, the miscalculation of Islam, and the war being used a "major recruiting tool for Islamic extremists".
The Evangelical Leaders Survey is a monthly poll of the 100-strong board of directors of the National Association of Evangelicals in the US. They include the CEOs of 60 denominations and representatives of a broad array of evangelical organisations including mission groups, universities, publishers and churches.
