Lot of Mahatma Gandhiji's quotes have been misunderstood or discussed out of the context (from which it was told) -so there is always a fair bit of discussion on exactly what he has meant.
Maybe we never know on what context he made those comments - but I am sure it will be with respect to two main principles he fought (non-violence and against untouchability ) - vis-a-vis the stand of Christ and Christians on it. (At that time - during early 1910-1940's)
The comment surely should not be associated in religious context but with respect to the prevailing social differences at that time, especially South Africa and India.
Hope I am making my point clear.
And, BTW, when I googled I happened to stumble on this site which might also give some other perspective