Reviewed by Alexander Lucie-Smith Father Paul’s War ALLIANCE PUBLISHING PRESS, 332pp, £8.99Tablet bookshop price £8.10 Tel 01420 592974 A Tear in the CurtainSHEPHEARD-WALWYN, 208pp, £9.95Tablet bookshop price £9 Tel 01420 592974  Here are two historical novels which deal with Communism, the first in China, the second in Europe, and both of which leave the reader in no doubt that the sufferings caused by Marxism are among the worst that humanity has ever endured. Mark Cheng’s Father Paul’s War centres on a young Chinese engineering student at the University of Peking before the Second World War. Taught by a Jesuit, he becomes a Catholic, and then later a monk at Our Lady of Consolation, a Cistercian monastery about 80 miles from the cit