BUT I thought I could lose my salvation.
God says
"Most assuredly, I say to you, he who hears My word and believes in Him who sent Me has everlasting life, and shall not come into judgment, but has passed from death into life."
The Gospel of John
Chapter 5, Verse 24
And Jesus said to them, "I am the bread of life. He who comes to Me shall never hunger, and he who believes in Me shall never thirst All that the Father has given Me will come to Me, and the one who comes to Me I will by no means cast out. For I have come down from heaven, not to do My own will, but the will of Him who sent Me. This is the will of the Father who sent Me, that of all He has given Me I should lose nothing, but should raise it up on the last day."
The Gospel of John
Chapter 6, Verses 35, 37-39
That means
There is no way salvation can be lost. Jesus said that the person who believes in Him shall not come into judgment. Thats a promise. If a person who had everlasting life ever "came into judgment," then Jesus would not be true to His word. Yet it is impossible for God to lie.
Many people think that staying saved is a matter of their doing Gods will. However, Jesus Christ said that it is really a matter of His doing Gods will! Jesus promised that whoever believes in Him will never hunger or thirst. Never. He promised that He will by no means cast out anyone who comes to Him and that He wont lose even one person who has believed in Him.
If anyone who came to faith in Christ ever lost his or her salvation, then Jesus would have failed to fulfill His promise and to do the will of the Father. Christs eternal gift can never fail for any reason. He guarantees it.