Spiking neural networks (SNNs) offer a promising pathway to implement deep neural networks (DNNs) in a more energy-efficient manner since their neurons are sparsely activated and inferences are event-driven. However, there have been very few works that have demonstrated the efficacy of SNNs in language tasks partially because it is non-trivial to represent words in the forms of spikes and to deal with variable-length texts by SNNs. This work presents a "conversion + fine-tuning'' two-step method for training SNN for text classification and proposes a simple but effective way to encode pre-trained word embeddings as spike trains. We show empirically that after further fine-tuning with surrogate gradients, the converted SNNs achieve comparable results to their DNN counterparts across multiple datasets for Both English and Chinese. We also demonstrate that such SNNs are more robust against adversarial attacks than DNNs.