Calling Christians to Islam
27-3-2006 | IslamWeb
Question:
I want to convince a Christian to embrace Islam with evidence, how would I tackle the issue?
Answer:
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.
Calling the Christians to Islam should be based on two foundations:
The first foundation: Clarifying that Islam is the true religion and that it is the religion of all the Prophets, may Allaah exalt their mention, and that each Prophet used to confirm the message of other Prophets who came before him. For instance the religion of Islam which was revealed to the Prophet 
confirms what was revealed before to Moosaa (Moses) and 'Eesaa (Jesus), and other Prophets before them, may Allaah exalt their mention. Even though some legislations differed but the principle of religion is one, which is the call to the Oneness of Allaah and to worship Him Alone without any partners, and that He is Perfect and above all forms of deficiencies. That is why Allaah considered a person who denies one Prophet as if he denies all the Prophets; this is so often repeated in the Quran. Allaah Says (what means): {‘Aad denied the messengers.}[Quran 26:123]. Allaah further Says (what means): {The companions of the thicket [i.e. the people of Madyan] denied the messengers.}[Quran 26:176]. Although, only one Messenger was sent to ‘Aad, Thamood and the companions of the thicket; but whoever denies one Prophet, he disbelieved in all of them. This is one reality that one has to make clear to the Christians, and that 'Eesaa (Jesus) 
gave glad tidings about the Prophet . Even their bibles testify to this effect despite them being forged and falsified. So one has to clarify to the Christians that disbelieving in Muhammad is disbelieving in 'Eesaa .
Moreover, when clarifying that the religion of Islam is the truth, one has to make the following matters clear:
1- Islam corresponds with the natural predisposition upon which Allaah created mankind.
2- Islam also corresponds with sound mind and sound reasoning. If one properly ponders on this universe, he will ultimately believe that this universe must have one Creator. Allaah Says (what means): {Had there been within them [i.e. the heavens and earth] gods besides Allaah, they both would have been ruined.}[Quran 21:22].
3- The evidences about the truthfulness of the Prophet among which is the Quran, a Book which was preserved along the centuries from any falsification and distortion. Indeed modern science proves every day that the realities that are mentioned in the Quran are the truth although it was brought by the Prophet who used to be a shepherd in Makkah.
4- Clarifying the advantages of Islamic religion and its excellence; some books were written on this subject.
The Second Foundation: Clarifying the falsehood that the Christians are upon and that what whey believe in, is forged and falsified, and reveal the deficiencies, discrepancies and disadvantages of their wrong belief, and they are so many.
Allaah Knows best.