Based on the presented sources, leaving the Orthodox faith—that is, switching to another religion or refusing to participate in the sacraments of the Orthodox Church—is viewed as a risk of losing grace and, consequently, as a possibility of the soul ending up in hell.

The Eternal Risk of Abandoning Orthodoxy

Based on the presented sources, leaving the Orthodox faith—that is, switching to another religion or refusing to participate in the sacraments of the Orthodox Church—is viewed as a risk of losing grace and, consequently, as a possibility of the soul ending up in hell.

In one of the cited sources, it is stated:"How can an Orthodox person lose grace?

If he switches to another faith, if he takes communion in another faith, if he worships foreign gods or recites any pagan mantras. In such a case, the person loses the grace of Orthodoxy. And to return, he must undergo a special rite known as the Rite of Reconnection. The Church is merciful; it does not turn people away and accepts those who repent. But undertaking such experiments on one’s soul is very dangerous, because the person might not live to see the Rite of Reconnection, thus perishing in his delusion, and his soul will suffer terribly in hell. As the Scripture says: '...there will be weeping and gnashing of teeth' (Matt. 13:42)" (source: link txt).

Another quote underlines the importance of remaining in sacred union with the Orthodox Church and links being outside of it with a path leading to destruction and eternal torment of souls:

"The importance and necessity of remaining in union with the Orthodox Church and the danger for those living outside this sacred union. Saint Zadon urges Christians to observe and keep all the promises made when they embraced it... Thus, remaining outside the bosom of the Orthodox Church logically leads to the path of destruction and eternal torment for souls" (source: link txt).

Thus, according to the presented materials, a conscious renunciation of the Orthodox faith—evidenced by a change in belief, a loss of participation in church sacraments, and ultimately a break in the spiritual union with the Church—is considered a risk to the salvation of the soul. When a person, aware of his spiritual responsibility, breaks this union, he risks remaining outside the grace, which in turn can lead to eternal torment in hell.