How can a young man remain steadfast in Allah's religion while abandoning some of his obligatory duties, repeatedly repenting and relapsing, and fearing that Allah might take his soul in this state?

Mere intention is not enough for rectitude; rather, it must be coupled with serious effort and true uprightness. This involves adopting the means to achieve rectitude, which include: accompanying the righteous and changing bad environments, continuously feeling dependent on Allah and supplicating with sincerity, striving against the self by not surrendering to Satan, preserving supererogatory acts of worship after obligatory ones, consistently reciting the Quran with contemplation, reflecting on Allah’s names and attributes, pondering death and what comes after it, and staying away from everything that leads to disobedience and neglecting duties.