This has been bothering me for a long time, if Christianity is the true religion, why are there Christians converting to Islam?
The fact that Christianity is the true religion (ie that is tells the correct story about God) does not prevent people from being Hindu, Buddhist, Confucionist or Islamic. People reject Christianity for any of a number of reasons. It is not possible for me to give a single answer which does justice to the question or to the various reasons for different people. I will guess that, outside of Islamic countries where it is illegal to convert to Islam, there are more conversions from Islam to Christianity than from Christianity to Islam. Nevertheless, some "Christians" have converted to Islam. One famous example is the entertainer formerly known as Cat Stevens (now known as Yusuf Islam). In his own words, it was a brush with death that started him on a spiritual journey which led him to conversion to Islam in 1978. The fact the a person converts to Islam tells us absolutely nothing about whether this religion is the truth. Neither does the fact that a person converts from Islam to Christianity. There are attractive elements in all major religions, otherwise they never would have spread and become so popular. In the case of Islam, things which are "attractive" include the simplicity of its form of worship, the beauty of the poetry in the Koran, the moral lifestyle held up by the religion and the sense of community generated by the religion.