Perhaps I can suggest you a reading on Cadre Policy, by Chen Yun

While carrying out criticism, we should know whether those who are criticized are old or new party members and whether they are old or new cadres. We should also know whether they have been members of the CPC or the revolution for a long time. With regard to an old party member, we can criticize him without paying too much attention to manner and means. However, this is not the case with new party members. Due to the fact that they have just joined the party, their mentality is still different from that of old party members. Therefore, when criticizing them, we should adopt a gentle manner. We should try to persuade and talk them into coming around.

In a word, we should encourage people to speak up. To do so, we should avoid pinning big political labels randomly. We should not deal with every minor mistake from the higher plane of principle. We should sincerely criticize people out of good will and in a friendly way. In the meantime, we should point out the cause of the mistakes and the way to correct them.

Also here's an inspiring story on why you shouldn't give up on people so easily I would like to highight:

When we were working in the soviet area^[The central soviet area, the key soviet area, and the soviet area in Jiangxi mentioned in this article refer to base areas of the provisional central government of the Chinese Soviet Republic led by the CPC with Ruijin as a center. These areas were established during the second revolutionary civil war. They were the so-called central revolutionary base areas. They were located in the southern parts of Jiangxi and the western parts of Fujian. They once governed 21 counties and had a population of about 2.5 million.] in Jiangxi, there Comrade Mao Zetan^[Mao Zetan (1905-1935) was from Xiangtan, Hunan Province. He joined the CPC in October 1923. After the failure of the first revolutionary civil war, he took part in the Autumn Harvest Uprising and went to the Jing Gang Shan. He was once a member of the CPC special committee in the northeastern parts of Jiangsi, secretary of the Zhongxin County CPC Committee, division commander of the independent division of the Red Army, secretary general of the Central Bureau of the CPC in the soviet areas, secretary of the Fujian Provincial CPC Committee, and military commander of the Fujian, Guangdong, and Jiangxi Military Region. After the main force of the Red Army carried out the Long March, he stayed in the south to persist in the guerrilla war. In April 1935, he heroically died in Ruijing when fighting against the enemy.] was working with us. He was a younger brother of Chairman Mao. He once committed a mistake; some people could not tolerate him and thought that he could not be used any longer. Later, the Red Army needed people to work because of expansion and he was sent to a certain district. He not only accomplished the tasks, but also performed his duty outstandingly and achieved great success. When he returned, many thought highly of him. He was transferred to a guerrilla area on the borders of Fujian and Jiangxi. Several months later, some people thought that he expressed remarks which seemed to be in line with right opportunism. Just at that time, a task in expanding the Red Army was assigned to him. Since he could not achieve good results, some people again thought that he could not be used. Nobody wanted such a person and he was rejected everywhere. No place wanted such a comrade and he could not even make a living. Later, when the Red Army retreated from Jiangxi, he laid down his life bravely in the battle and shed the last drop of his blood for the revolution. Therefore, when judging a person, we must not confine our judgment to a short period or a single incident in his life. If we fail to make a basic assessment of a person, we will commit very great mistakes in using people.

My own two cents: Remember that Marxism-Leninism is based on Materialism. I'm sorry to sound like a broken record, but like, when you're pitching it to someone don't forget to remember not just collective benefits, but how would those benefits serve the person you're talking to, how would they make their life better.

There's an old running joke how you can explain communism in great detail and people will think "Heck yeah, that's pretty cool" until you mention what it is, by name, and then they will gasp so imo. you should focus on getting people on your side and then you can use the big words once you have them interested.