In the mid 1500s, many Socinian unitarians were suspected of having Islamic leanings. Socinians praised Islam, though considering the Qur'an to contain errors, for its belief in the unity of God. Bilal Cleland claimed that "an anonymous writer" in A Letter of Resolution concerning the Doctrine of the Trinity and Incarnation (1693) states that Islam's greater number of adherents and military supremacy resulted from more closely maintaining correct doctrine than mainstream Christianity.[97]