How do I greet a Muslim friend of mine? I'm not Muslim, but I am reading and learning about Islam.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

First of all, we welcome you and we thank you for visiting our site, and we hope you will continue visiting it and ask about any question you might have. We will endeavour to the best of our ability to answer your questions.

As regards your question, the greeting of Islam is Assalaamu 'Alaykum wa rahmatu Allaahi wa barakaatuhu. This is a great form of greeting as it comprises the good of this life and the Hereafter. That is because this greeting includes a supplication to be free from defects and evil, and includes a supplication for mercy and goodness for the greeted person. So we advise you to greet this Muslim person with this form of greetings. However, it should be noted that it is a condition for actions of worship to be accepted by Allaah that a person should be a Muslim, as the actions of a non-Muslim are not accepted.

On this occasion we advise you to endeavour to embrace Islam as it is the true religion and a person is obliged to follow it in order to achieve happiness and success in this world and the Hereafter. It is the way leading a person to Paradise, Allaah willing, whose width is like the heavens and the earth, and in it are countless forms of enjoyment. In paradise there is what eyes have never seen, what ears has never heard of, and the minds or hearts of the people can never perceive. Furthermore, if one embraces Islam, he saves himself from the punishment of the Hellfire and the severe and unbearable torture therein. 

Finally, for more benefit, you may refer to Fataawa [plural of Fatwa] 88906, 88276, 88176, 86091, 81979 and 85234 all of which are about Islam.

Allaah Knows best.