[annalex]

does Catholic teaching, teaches us that the Holy Spirit of God is sealed inside of us until redemption?

Of course is does. Baptism, Confirmation and Holy Orders are indelible marks of the Holy Spirit. One cannot get unbaptised, for example.

[Forest Keeper]

[Harley on Eph. 4:30:] "... does Catholic teaching, teaches us that the Holy Spirit of God is sealed inside of us until redemption?"

Of course is does. Baptism, Confirmation and Holy Orders are indelible marks of the Holy Spirit. One cannot get unbaptised, for example.

But I thought that in Catholicism the Holy Spirit leaves the believer upon any mortal sin because we are no longer "in Christ" until confession. That sure sounds like an "unsealing" to me, in line with the Catholic belief that there can be no assurance in salvation. The believer can have no security, in contravention of Eph. 4:30.