It is necessary
δεῖ, ὀφείλω.δεῖ, the third person of δέω, is commonly used impersonally in classical Greek. This usage is less common, but frequent, in the N.T. δεῖ indicates a necessity in the nature of things rather than a personal obligation, it describes that which must be done. ὀφείλω indicates rather the personal obligation, it is that which is proper, something that ought to be done.