1 Jn. 1:2 has a neat little chiasm:
We have seen
We have witnessed
We have proclaimed
Life (eternal with the Father) manifested
The center of the verse is the word “witnessed” or “martyred.” This suggests a progression: first there is seeing, then there is dying, then there is proclaiming. Jesus has come and manifested life, but it is not until He has been seen, crucified, and announced that the life of the Father is manifested in its fullness. Likewise, our evangelism, our proclamation must consist of the same: we are only able to manifest life as we see, die, and proclaim this life.
Having seen the truth, we must be tested, tried, persecuted, die to sin, die to the flesh, suffer with and for Christ, and only then will our proclamation go forth as a full manifestation of the eternal life of the Father.