This is an interesting question. One that I didn't know the answer to and had to do some research myself. On searching the internet, sites like answering-christianity.com seem to suggest that Christianity excludes women from being witnesses. And Deuteronomy 19:15-19 is given as evidence.
One witness shall not rise against a man concerning any iniquity or
any sin that he commits; by the mouth of two or three witnesses the
matter shall be established ... The judges shall investigate thoroughly, and if the witness is proven to be a liar who has falsely accused his brother, you must do to him as he intended to do to his brother. [Deuteronomy 19:15]
However, I don't see how that passage explicitly forbids women from being a witness, or equates two women to one man. The passage is in masculine form and talks about
man. But it would apply to both genders just as the proverb - practice makes a man perfect - would.
I could not find any passages that specifically forbid women (perhaps there are and I missed, I look forward to other answers).
So, all I can do is give you passages that are somewhat related and show the role of women under the Christian perspective, which is based on how Christ treated women.
- The disciples were eyewitnesses to Christ's resurrection. The reason why he appeared to them and didn't just go straight to heaven after his resurrection, is so that they could be his witnesses.
... and you will be My witnesses in Jerusalem, and in all Judea and
Samaria, and to the ends of the earth [Acts 1:7]
... one of these must become a witness with us of His resurrection [Acts 1:22]
Interestingly he chose his women disciples to be the very first witnesses to his resurrection, which was strange given that they were less likely to be believed.
... Mary Magdalene, Mary the mother of James, and Salome ... When they
entered the tomb, they saw a young man dressed in a white robe sitting
on the right side, and they were alarmed. But he said to them, “Do not
be alarmed. You are looking for Jesus the Nazarene, who was crucified.
He has risen! ... But go, tell His disciples and Peter, ‘He is going ahead of you into Galilee. There you will see Him, just as He told you.’"
Early on the first day of the week, after Jesus had risen, He
appeared first to Mary Magdalene, from whom He had driven out seven
demons. She went and told those who had been with Him, who were
mourning and weeping. And when they heard that Jesus was alive and she
had seen Him, they did not believe it.
- Christ directly taught women (Martha and Mary) and did not treat them differently from men, which was very atypical of those times and often surprised people.
John 4:27 Just then his disciples returned and were surprised to find
him talking with a woman. But no one asked, “What do you want?” or
“Why are you talking with her?” [John 4:27]
- Apostle Paul says that men and women are not to be treated differently:
There is neither Jew nor Greek, slave nor free, male nor female, for
you are all one in Christ Jesus. [Galatians 3:28]
- God appointed a women called Deborah as a Judge:
Now Deborah, a prophetess, the wife of Lappidoth, was judging Israel
at that time. And she would sit under the Palm of Deborah between
Ramah and Bethel in the hill country of Ephraim, where the Israelites
would go up to her for judgment.
To me this shows that if you could sit as a judge in a court deciding cases, you could certainly be a witness.
It would be interesting to see if any Church fathers have written about this or if there's something in the Canon law. Hope someone else posts an answer.
Since you're coming at it from an Islamic perspective I want to take a moment to clarify the difference between Judaism and Christianity.
During my research, I found that some critic sites pointed to the common custom in Israel during the time of Christ, when women were not eligible to be witnesses. However, I believe those customs were based either on a different interpretation of the Old Testament, or on supplementary texts that are not accepted in Christianity. Christians belive Christ came to explain and clarify the law and interpret the scriptures in light of the New Testament (teachings of Christ).
I was able to find some verses from Jewish scriptures that don't allow women as witnesses.
The oath of testimony is conducted with men and not women [Mishnah (Shevuot 4:1)]
And this is applicable in all places and at all times, for males but
not for females because women are not included in the laws of
testimony due to the lightness of their intellects. [Mitzvah # 122]
However, these texts are not part of the Christian canon.