Newt had a lot of past infidelities and multiple divorces to put behind him. His conversion may have been sincere, but it was also convenient.
God forgives and forgets.
Evidently some people cannot believe that someone really converts in their mind, soul, and heart.
It would be as if an anti-Catholic (known to all of us) who posts anti-Catholic threads, all of a sudden studies some more and becomes a Catholic!
Find the truth, find forgiveness, please.