Whose spirit puts us in harmony with God?

Romans 8:9-10 NWT

You, however, are in harmony, not with the flesh, but with the spirit, if God’s spirit truly dwells in you. But if anyone does not have Christ’s spirit, this person does not belong to him. But if Christ is in union with you, the body is dead because of sin, but the spirit is life because of righteousness.

God's spirit or Christ's spirit?