We receive salvation when we believe in Jesus as Savior (Ephesians 1:13).
We are then marked in Christ with a seal (verse 13).
This seal is the Holy Spirit (verse 13).
The Holy Spirit is a deposit (verse 14).
This deposit guarantees our inheritance (verse 14).
With this inheritance we have redemption (salvation) (verse 14).
What about Hebrews 6:4-6 and Hebrews 10:26-27?
Our salvation is forever (John 10:27-29; 2 Corinthians 1:21-22; 1 Peter 1:23).