Yes, every Christian Communist out there is either a liberal or a covert atheist. \s

No, and even if you take it as true that communism and religious belief are diametrically opposite (which others here have pointed out is not necessarily true), it's still possible for that unresolved contradiction to exist within a person's ideology. To treat them as mutually exclusive is itself anti-dialectical. There have even been religious deviations of Marxism.

I recommend Lenin's "The Attitude of the Workers’ Party to Religion" if anybody is conflicted over this. Some excerpts:

It cannot be asserted once and for all that priests cannot be members of the Social-Democratic Party; but neither can the reverse rule be laid down. If a priest comes to us to take part in our common political work and conscientiously performs Party duties, without opposing the programme of the Party, he may be allowed to join the ranks of the Social-Democrats; for the contradiction between the spirit and principles of our programme and the religious convictions of the priest would in such circumstances be something that concerned him alone, his own private contradiction; and a political organisation cannot put its members through an examination to see if there is no contradiction between their views and the Party programme.

[...] We must not only admit workers who preserve their belief in God into the Social-Democratic Party, but must deliberately set out to recruit them; we are absolutely opposed to giving the slightest offence to their religious convictions, but we recruit them in order to educate them in the spirit of our programme, and not in order to permit an active struggle against it. We allow freedom of opinion within the Party, but to certain limits, determined by freedom of grouping; we are not obliged to go hand in hand with active preachers of views that are repudiated by the majority of the Party.

On the other hand, the tradition of bourgeois war on religion has given rise in Europe to a specifically bourgeois distortion of this war by anarchism—which, as the Marxists have long explained time and again, takes its stand on the bourgeois world-outlook, in spite of all the “fury” of its attacks on the bourgeoisie. The anarchists and Blanquists in the Latin countries, Most (who, incidentally, was a pupil of Dühring) and his ilk in Germany, the anarchists in Austria in the eighties, all carried revolutionary phrase-mongering in the struggle against religion to a nec plus ultra. It is not surprising that, compared with the anarchists, the European Social-Democrats now go to the other extreme. This is quite understandable and to a certain extent legitimate, but it would be wrong for us Russian Social-Democrats to forget the special historical conditions of the West.

In short, there's a time and a place to struggle against religion.