One of the reasons why Lenin changed Marxist ideology was that there was an unfinished revolution. According to Marxist ideology there would be a revolution where the proletariat all over the world would rise up and over throw the leaders and after the revolution the whole world would become communist. This didn’t happen following the revolution in 1917, so Lenin had to change the ideology, as it didn’t offer any alternatives if something didn’t work. The people still needed something to believe in ad an ideology to follow so Lenin changed it.
Another reason was the new economic policy. This was introduced to make sure that there was enough grain for the proletariat as if there wasn’t enough grain then they would starve and they wouldn’t want to revolt. The NEP however was a very capitalist idea, which Lenin justified as it was keeping the Bolsheviks in power which according to Lenin was because you have to keep the peace in order for there to be a revolution which was the ultimate goal “the ends justify the means”
Another way to keep the peace was the treaty of Brest-Litovsk. This was a treaty made with Germany to stop them fighting with Russia. Russia gave Germany whatever they asked for, as they were so desperate for peace so their revolution could take place. Giving up everything was against the Marxist ideology; however also in Marxist ideology was the phrase “the ends justify the means” which meant that that as long as what Lenin was doing would result in a worldwide revolution then it was justifiable.
In conclusion, I think that the main reason for Lenin changing Marxist ideology was because there was an unfinished revolution. This is the main reason because if there had been a worldwide revolution of the proletariat then there would have been no reason to change the Marxist ideology. I also think that the other changes to the ideology wouldn’t have happened if there had been a full revolution.