From 中国哲学的特质, it is plain that Prof Mou has a good grasp of issues in both modern European Philosophy and Christianity.
This is unsurprising. While Prof Mou studied in Beijing (and never lived in Europe or America), his academic speciality is in Western Philosophy broadly conceived.
His undergraduate institution, Peking University, was a leading university of his time, likely the most prestigious in China. He must have been one of the very brightest Chinese students and scholars of his generation.
But I think he misses some nuances in Christian thinking and sometimes resorts to (what seems to me) broad stroke descriptions of Christianity that are just too quick.
(I bear in mind fully that the quotes are from his oral lecture notes and (in his own words) are not as well-thought out as his writings would be. I also bear in mind that Prof Mou has left us and these comments are really addressed to scholars following in his footsteps.)
在道理上说，耶教只有向上逆返，而无向下顺成，故为不圆之教。而天命、天道下贯于人心而再于具体生活中作顺成的表现，这一回环正由中国的大圣人孔子所完成。由此可言：儒耶合作，可使天人关系的道理圆融通透。
Most Christian / Christian-influenced readers at this point would think: well, what about the eucharist? What about prayer? Surely it is a somewhat one dimensional view of Christianity to think we never argue with God (Book of Job; Jesus’s words on the cross “my God, my God, why have you forsaken me”)?
In a similar vein, the following comment seems to have ignored the contributions of figures such as Matteo Ricci.
然而，自古宗教信仰都有极强烈的排他性，圣人教主之中无二人能够合作。从文化立场来看，这可说是圣人的悲剧，宗教信仰的悲剧。这些悲剧不可消灭，我们唯有给予无可奈何的悲悯。由于不同的宗教信仰互相排斥，永不相解相谅，所以宗教容易沦落。
For myself, I see relatively little that is incompatible between the teachings of Confucius and Christianity.
They are just addressing fundamentally different concerns. Confucianism is predominantly about our place in the political order (being an intended ideology of the ruling class from inception). Christianity is a more complex mix of ideas, many having little immediate bearing with practical political or even specific moral action.
Confucianism tells you to follow the predominant 禮, ie the pre-existing customs and moral order from time immemorial. By contrast, there is a tension from the start whether as a Christian, you are supposed to follow Jewish, Greek, Roman or some other standards of conduct. Even St Peter got it wrong: he thought the Jewish-Gentiles distinction should be kept, only to be told off by St Paul (who incidentally never met Jesus before the crucifixion).
In many ways, Confucianism makes sense in a way that Christianity does not.
內聖 and 外王 fit together nicely, and are very practical and admirable projects to undertake. Christianity is (again) much more of a mix bag of ideas, eg like non-political eucharist-based worship, “precatory” prayer (i.e. asking for things we want), and charity even towards people who are undeserving (eg criminals).
It is perplexing to me why Prof Mou sees the two traditions as somehow in tension with each other in the first place.
I understand Prof Mou’s frustration at scholars who claim that China has no Philosophy: a reaction which should be situated in the broader cultural scene where some Chinese intellectuals were radically attacking their own culture.
But one should not do down other schools of thought simply to elevate one’s own. Dialogue between groups who subscribe to different foundational canonical texts should proceed on the basis that neither is seeking to convert the other. Otherwise the exercise is apologetics not dialogue.
Another example of a somewhat careless sketch of Christianity,
只是祈祷上帝加恩、上帝赦免、上帝助我、上帝救我，这并无助于自己生命之清彻。这虽不无刺激提醒之切，在祈祷中，有忏悔的心理，内心之明无形中也透露了一点，但因情之外逐，一切求之于上帝，不能回鉴反照，自己生命仍然是幽昧混沌。不能回过头来正视那内心之明，求有以彻底实现之，则对于道德之善并无清楚的意识，对于罪恶亦并无清楚而具体的观念，因而亦并不肯自己负责作那「从根上彻底消化那生命中之非理性反理性的成分」之工夫。祈祷并不真能代表或代替这种内圣的工夫。这工夫是真要自己去作的：先在忏悔中正视那知是知非的内心之明——那超越的内心之明，步步彰显之。先在这里定住，不可转眼间又滑到上帝那里去。把这内心之明又堵回去了，弄糊涂了，此时最好先把那上帝忘掉。如是，才能把那无形中露出的一点内心之明予以正视，变成自觉的。
Again, I have full respect for the Confucian mental exercises Prof Mou recommends. But why the criticism of prayer for Christians?
In any case, Christians are supposed to ask God for what they want , however discreditable, not what they are supposed to want (eg passing exams; cf Herbert McCabe). It is just wrong to see prayer as some defective version of 內聖: they are meant to do fundamentally different things.
Finally, and for completeness, the following is not an accurate description of mainstream Latin Western Christianity.
还有一点，在当时因时间关系，没有讲及，现在再附识于此。这一点就是关于「启示」的问题。基督教是上帝启示的宗教，上帝启示他自己于自然界，于种种奇迹，最重要的还是启示于耶稣，而成为基督教，这也是以上帝为中心而展开的教义。依这种说法，耶稣是神而不是人。他是上帝的唯一化身（道成肉身），唯一圣子（独生子），圣子只有一个。上帝可能有许多化身，但是上帝化身为谁，这是上帝的旨意，不是人所能决定的。可是依基督教，他们说上帝只化身为耶稣。他们已很清楚地知道这是上帝的意旨，这个意旨是已经确定了的。至于他们何以知道上帝的意旨只是如此，这是很难说得通的，这点我们且不追问。我们所注意的，是启示。当然我们也可以视耶稣为人（当然不是普通的人）。但依基督教，耶稣之人的身分或地位，是偶然的。即，其本质是神，而不是人，因此其为神的地位是必然的。他是神化身而为人的样子，以与世人照面。从其为人的样子说，他当然是人；但其本质是神，他的生命全幅是神性，故云上帝的「化身」。因此，他所以是如此之生命，这是上帝的意旨所决定的，这是上帝所差下来的。这是天启、天意，并不是由于他的修养工夫而至的。即不说修养工夫，也不是直下肯定他是人，说他是由人而成的。
Whether you think it makes sense or not, the Chalcedonian Creed says Jesus is “truly God and truly Man”: 耶稣之人的身分或地位，是偶然的。即，其本质是神，而不是人，因此其为神的地位是必然的。 is just wrong as a characterisation of what Catholics and Protestants believe when they recite the Creed.
For the early Christians, this was not mere quibble, as the idea that Jesus was truly God and not truly Man was associated with theories and political movements (eg Gnosticism) that were deemed heretical and led to religious wars. Professor Mou’s criticism may be entirely right as against Gnosticism, but it is not on point as regards Catholicism or Protestantism.
To say the above is not to say that Prof Mou’s contributions are not valuable. I am not qualified to and do not comment on his work on Chinese Philosophy: there is no reason to doubt that the mainstream consensus of his greatness. But the comments about Christianity are just not on point.