# suffered for us

The word "us" includes the people Peter was writing to; as he explains how Christ suffered and what Christ accomplished by suffering.

# so that he would bring us to God

Peter probably means here that Christ died in order to create a close relationship between us and God.

# He was put to death in the flesh

"People put Christ to death physically" 

# he was made alive by the Spirit

"the Spirit made him alive" or "he was made alive in the spirit" or "he was made alive with a spiritual body"