The shop had been facing mounting criticism after it emerged a pastor's wife was blocked from leaving a message on a bouquet of flowers because she wanted to say "with love from Christ Church Teddington".
M&S initially said the words were on an "automatic phrase checker to prevent their misuse".
A spokesperson for Marks & Spencer said: "We apologise for any offence caused, it was certainly never our intention. We have revised the words included on the automatic phrase checker which is in place to prevent the use and misuse of certain words."
The message facility had disappeared from the website after an initial media enquiry although a spokesman for M&S told Premier this was not related to this issue and it was now working again.
Premier found terms like Allah, Mohammad, Buddha and jihad were allowed but not Jesus Christ.
Gerardine Stockford, who originally discovered the restriction, told Premier's News Hour: "I was really shocked. Why should it be a word that you would block? It didn't make any sense to me.
"You know, having thought about it afterwards, how can it be that particularly in a Christian country you can remove the name of the central figure in the Christian faith?
"It does beggar belief really that they thought it necessary to actually do that. Indeed, I find it hard to believe anybody would want to send any offensive words to somebody if you're sending them a gift, so none of that really makes sense to me.
"It seems that the right use of the word in this case has been trumped by the use that some people - and not the majority of people - make of it as an expletive.
"I think it's good they've done it [removed the restriction]. To my mind it doesn't matter how long it takes as long as they have agreed, they've discussed it thoroughly, and they've come to the decision - rightly - that it's unacceptable to prevent somebody from using a perfectly acceptable word."
Christian Concern said: "We are delighted that Marks and Spencer has responded to the huge concern raised by members of the general public on this matter and will no longer 'blacklist' the name of Jesus Christ as a swear word or one that gives offence, Jesus Christ is the most pivotal figure in our nation's history, His name captures God's redeeming love for all people and it is remarkable that it was ever banned."
Listen to Gerardine Stockford speaking to Premier's Antony Bushfield on the News Hour:
