I believe in the seven churches as ages...
Ephesus - Messianic - Beginning with the Apostle to the Circumcision, Peter
Smyrna - Martyr - Beginning with the Apostle to the Un-Circumcision, Paul
Pergamos - Orthodoxy formed in this time... Pergos is a tower... Needed in the dark ages
Thyatira - Catholicism formed in this time - The spirit of Jezebel is to control and to dominate.
Sardis - Protestantism formed in this time- A sardius is a gem - elegant yet hard and rigid
Philadelphia - Wesleyism formed in this time - To be sanctioned is to acquire it with love.
Laodicea - Charismatic movement formed in this time - Beginning with DL Moody, the first to make money off of ministry
In which, as the salvation issues arose out of the Sardisean church age, the Lord Jesus also comments on the issue...
He that overcometh, the same shall be clothed in white raiment; and I will not blot out his name out of the book of life, but I will confess his name before my Father, and before his angels. - Revelation 3:5
I would imagine the Lord Jesus saying, "If you overcome... Yes, the eternal security is yours!"
That is fine. I believe the seven churches speak to church ages also. But, that doesn't mean they were not literal churches with the very problems that John addressed.
And who is the overcomer? The same writer of Revelation said so earlier in his book of (1 John). (1 John 5:5) "Who is he that overcometh the world, but he that believeth that Jesus is the Son of God? So yes, if you have placed faith in Jesus Christ as your Lord and Saviour, your eternal life is secure.
I am always amazed at how Christians take (Rev. 3:5) to mean God can blot their name out of His book of life, when Jesus said specifically, that he will 'not' blot their name out.
Stranger