Are you sure it's a recognize charity. It could be a scam or an organization not eligible to receive tax deductible contributions. examples: a PAC, foreign charity. https://www.irs.gov/charities-non-profits/tax-exempt-organization-search
if you don't find it using the above link you can always ask them for a copy of their exemption letter.
Thank you for answering. It is my church that I could not find a charity code for.